
aass, S4-^£ " 
^H6 



ol 

id, 

d, 

List 
or 
is 



at 
ry 
ni, 

of 
an 
ire 



■ed 
to replace by a new dook any uuui^ i'-'Hl or 
damaged bv'their children or wards, within 
ten davs after receiving a written notice from 
the teacher, and in case of a neglect or refnsal 
to replace the book within a specified time, 
the pupil in whose possession the lost or 
damaged book was placed shall be deprived of 
all books furnished by this County until this 
Rule be complied with. Teachers are reqnired 
to strictlv enforce this Rule. 




THE 



PRINCIPLES OF AGRICULTURE 



COMMON SCHOOLS 



BY 



I. 0. WJNSLOW, A.M. 



NEW YORK :• CINCINNATI •:• CHICAGO 

AMERICAN BOOK COMPANY 






Copyright, 1890, 
By I. O. WiNSLOw 



•*1N. AG. 



»»-^OiNQ ROOM 



PREFACE. 



A KNOWLEDGE of the principles of agriculture, 
which simply means a knowledge of the natural 
laws and principles which underlie rural life and rural 
pursuits, is not only important for those who are ac- 
tually engaged in the pursuits of agriculture, but may 
in general be regarded as an important element in the 
education of the young. 

For the large number of pupils who are unable to pur- 
sue an extended academic course of study, the natural 
sciences should not, as is too often the case, be wholly 
neglected. 

Although the time of the school course may not admit 
of a thorough mastery of any one of these sciences, a 
selection of the fundamental and elementary principles 
of each may be consistently and profitably presented. 

Education of this kind, impressing upon the young the 
mysteries and the beauties of nature, tends to increase 
the fondness for our native soil, and to develop a spirit 
of genuine patriotism. 

This book is designed primarily for use in the public 
schools, and contains no difficulties too great for ordi- 
nary pupils of twelve or fourteen years. 

(iii) 



iv PKEFACE. 

It has been the aim to observe a careful analysis, 
separating the subjects into distinct topics, and treat- 
ing each briefly and concisely. 

Many minor and subordinate topics have been pur- 
posely omitted. The experience of the author leads him 
to believe that a thorough knowledge of the few main 
points of a subject is worth more to the pupil than a 
confused idea of the whole. 

There are many problems connected with the subject 
of agriculture which have not yet been solved, and many 
points which have not been definitely settled. These 
are either wholly avoided or briefly mentioned. There 
is enough which is established beyond question to engage 
the attention of beginners. 

The first chapters of the work contain but little that 
belongs peculiarly to the science of agriculture, but they 
necessarily form the foundation of tliat science. They 
comprise some of the leading facts and principles of 
chemistry, natural philosophy, geology, physical geog- 
raphy, and botany, particularly such as bear directly 
upon agriculture and rural life. 

The questions at the end of each chapter are inserted 
for the especial purpose of assisting such teachers as are 
not familiar with the subjects, and do not feel competent 
to present them. As the work is arranged, it is believed 
that no teacher will find any difliculty in understanding 
it or making it interesting. 

June, 1891. 



CONTENTS. 



Pages 
Suggestions to Teachers 6 

CHAPTER I. 

The Substances of the Earth . . . 7-25 

CHAPTER H. 
Land and Water 26-40 

CHAPTER III. 
The Atmosphere 41-53 

CHAPTER IV. 
Plants 54-76 

CHAPTER V. 
Fertilizers 77-99 

CHAPTER VI. 
Cultivation 100-113 

CHAPTER VII. 
Animals 114-144 



Glossary c ..... 145-146 

Index 147-152 

(5) 



SUGGESTIONS TO TEACHERS. 



TRUE teaching requires activity and orij;inal work on the part of 
the teacher. To rely mainly upon the text-book, and simply 
require pupils to commit to memory the statements of the text, is not 
teaching. 

The aim should be to stimulate in the minds of pupils the habit 
of observing and thinking for themselves. The text should simply 
serve as a guide, or starting point, for the work of the class. 

This is particularly true of subjects related to the natural sciences, 
like those of which the present work is composed. Many topics in 
the text are necessarily treated with brevity, but it is expected that 
teachers will avail themselves of the opportunity to amplify and illus- 
trate them with familiar examples. 

The questions at the end of each chapter may be used for review 
exercises or for examinations. They may also be used in daily reci- 
tations, but teachers will naturally ask many similar questions of 
their own. 

The teaching will be rendered much more interesting and effectual 
by the free use of object lessons and simple experiments. Those 
who are accustomed to teach the natural sciences and are supplied 
with apparatus for the purpose, need no suggestions upon this point. 

The outfit of a chemical laboratory is not necessary, however, as 
the ingenious teacher will find abundant means for the purpose 
within reach. Specimens of rocks, soils, and plants from the neigh- 
boring fields, pots of soil with a few varieties of seeds and of fer- 
tilizers, for experiments in the growth of plants, a small quantity 
of some common and familiar chemicals purchased for a few cents of 
the nearest apothecary, and a small microscope, either purchased or 
borrowed for occasional use, are among the means available. 

It will serve a useful purpose, particularly with the older pupils, 
to have at hand, for reference and comparison, other works on chem- 
istry, geology, physical geography, botany, and agriculture. 

The subject is naturally interesting, and, if wisely presented, can 
not fail to afford enjoyment to both teacher and pupils, and to yield 
satisfactory results, 
(vi) 



THE PRINCIPLES OF AGRICULTURE. 



CHxiPTER I. 

THE SUBSTANCES OF THE EARTH. 

Simple Substances. — All matter of which the earth, the 
atmosphere, and all plants and animals are composed 
consists of a comparatively small number of simple sub- 
stances or elements. 

We are accustomed to think of the ordinary objects 
about us as simple in their nature, and as composed of 
but one kind of matter. 

This is true of a few substances, like pure gold, silver, 
and iron ; but the greater number of the objects with 
which we are familiar are ct)mposed of several simple 
substances mixed or combined. 

Water is composed of two gases. Wood may be di- 
vided into ten or more different elements. If we burn a 
pile of wood we see the smoke, we know that there are 
gases escaping which we cannot see, and we find a small 
quantity of ashes remaining. Neither the smoke, the 
gases, nor the ashes appear at all like wood, and yet we 
know that in some way the wood has been transformed 
into these substances, 

(7) 



8 



THE PRINCIPLES OF AGRICULTURE. 



The whole number of elementary substances at present 
known is from sixty-five to seventy. Some of them, how- 
ever, are very rare. 

Only fourteen elements are generally found in soil, 
plants, and animals. Knowledge of these is of impor- 
tance in the study of agriculture. 

They are as follows : — 



Oxygen . . 


. 


Chlorine . 


. CI 


Nitrogen . . 


. N 


Potassium . 


. . K 


Hydrogen 


. H 


Sodium . . 


. . Na 


Carbon . . 


. C 


Calcium 


. . Ca 


Silicon . . . 


. Si 


Magnesium 


. Mg 


Sulphur . . 


. s 


Aluminium 


. . Al 


Phosphorus . 


. p 


Iron . . . 


. Fe 



These names are used so often that, for convenience, 
they are abbreviated, each being represented by one or 
two letters. The abbreviations are called symbols. The 
symbols for potassium, sodium, and iron are taken from 
the ancient and foreign names of those substances. 

Atoms. — All matter is composed of minute particles 
called atoms. These are so small that they have never 
been seen. We cannot even imagine the size of them. 
Millions of atoms might rest upon the point of a pin. 

The belief that they exist is embodied in what is called 
the acomic theory. This theory is believed to be true, 
because all known facts are consistent with it. All the 
facts in nature with which we are acquainted, and the 
results of all experiments that have ever been tried, are 
just what they would be if the theory were true. The 
fact that atoms cannot be seen is no reason for doubting 
their existence. We are limited in our power to see 
and understand. As we are unable to comprehend the 
distance to the sun, and the immensity of space, so, on 



THE SUBSTANCES OF THE EARTH. 



9 




A Drop of Water. 

{Magnified.) 



the other hand, we cannot form any idea of the mhiute- 
ness of matter. 

Powerful microscopes have revealed forms of animal 
life which had never before been conceived of. It is 
known that multitudes of liv- 
ing beings may occupy a single 
drop of water. 

An atom is the smallest 
particle into which matter can 
be divided. We may repeat- 
edly subdivide a piece of gold 
until it is reduced to the 
thousand-millionth part of an 
ounce, and yet we shall be 
far from reachhig a single 
atom. If it were possible to 
continue the process long enough, a particle would finally 
be obtained which could no longer be divided or changed 
in any respect. 

An atom of oxygen is always exactly the same, whether 
it forms a part of the soil, or of the air, or enters into the 
structure of a plant or an animal. 

An atom is represented by the symbol which is used 
to denote the kind of substance. The symbol may 
denote a quantity of oxygen in general, or an atom of 
oxygen. A number of atoms is indicated by a figure 
written below, and to the right. 0,^ denotes two atoms 
of oxygen, Hg six atoms of hydrogen. 

Molecules. — Atoms do not generally exist alone. They 
possess a force of attraction which causes them to unite 
with other atoms, either of the same kind or of a differ- 
ent kind. 

This force is called chemical affinity. It causes atoms to 



10 THE PRINCIPLES OF AGRICULTURE. 

unite in regular groups. A group of this kind is called 
a molecule^ which means a little mass. 

Two atoms of hydrogen uniting with one of oxygen 
form a molecule of water. Twelve atoms of carbon, 
twenty-two atoms of hydrogen, and eleven atoms of 
oxygen, produce a molecule of sugar. 

Molecules, though larger than atoms, are yet too small 
to be seen. 

A molecule is . represented by writing together the 
symbols of the different kinds of atoms of which it is 
composed, giving the number of atoms of each kind. 
The expression H2O represents either a molecule of 
water or water in general. HgSO^ denotes sulphuric 
acid, and indicates that in a molecule of the acid there 
are united two atoms of hydrogen, one of sulphur, and 
four of oxygen. 

When more than one molecule is to be represented, 
the number is indicated by a figure prefixed. 2 COg 
represents two molecules of carbonic acid. 

In all molecules of the same substance the atoms are 
supposed to maintain a uniform order of arrangement. 

They always hold regular positions with respect to each 
other. The positions depend upon the relative degree 
of attraction which the atoms have for each other. 

The arrangements are supposed to be somewhat like 
the follo wing : —_ 

,Na-Cl. H-O-H. H-N-H. H-0-Ca-O-H. 

-,\(Salt.) (Water.) (Ammonia.) (Slaked Lime.) 

The Nature of Matter. — The nature of any substance 
depends upon the nature of the molecules of which it is 
composed. It may be entirely different from the sub- 
stances whose atoms unite to form the molecule. 



THE SUBSTANCES OF THE EARTH. 11 

Hydrogen and nitrogen are both odorless, but when 
united they form ammonia (NHg) which is noted for its 
strong odor. Chlorine alone is poisonous, but with sodium 
it forms common salt (NaCl). The great variety of dif- 
ferent kinds of matter is produced by the great number 
of possible combinations of atoms of the elementary 
substances. 

Chemical Action. — Molecules are the smallest particles 
into which a substance can be divided without changing 
its nature. Whatever change is wrought upon matter, 
its real nature remains the same so long as its individual 
molecules are not broken up. 

A substance may be melted, or converted into a gas, or 
mixed with some other substance, and yet it is the same 
substance ; but if its molecules are divided into their sep- 
arate atoms, and these unite again with other atoms in 
different combinations, it is no longer the same. 

The force which divides molecules into their separate 
atoms, and permits them to form other combinations, so 
as to produce new substances, is called chemical force, or 
the chemical action of one substance upon another. 

When two molecules of different kinds are brought to- 
gether, if some of the atoms of one are more strongly 
attracted by atoms in the other than by neighboring atoms 
in their own molecule, one or both of the molecules will 
be broken up and new molecules will be formed. 

When water is poured upon quicklime, the atoms 
of the water molecule unite witli those of the lime mole- 
cule, forming molecules of a new substance, or slaked 
lime. 

When some of the atoms are not needed in making up 
the new molecule they are set free. If pieces of zinc are 
placed in hydrochloric acid, the chlorine of the acid will 



12 THE PKINCIPLES OF AGRICULTURE 

unite with the zinc, and the atoms of hydrogen unite with 
one another, forming molecules of free hydrogen. 

Chemical force sometimes changes the nature of a 
substance by simply changing the arrangement of atoms 
in its molecules. The molecules of cane sugar, and 
those of gum arable, for instance, contain exactly the 
same number of corresponding atoms (CigH^^Oji). There 
are other instances in which the same is true. The only 
explanation of this is that the atoms must occupy different 
positions with respect to one another in the molecules of 
the different substances. 

Chemical Equations. — The action of chemical force in 
breaking up molecules of different kinds when they are 
brought together, and forming new molecules, is repre- 
sented by an equation. 

In the case of water and lime the equation is : 

CaO + HgO = CaOsH^. 

(Lime.) (Water.) (Slaked Lime.) 

For zinc and hydrochloric acid it would be : 
2 HCl + Zn = ZnCls + H^. 

(Acid.) (Zinc.) (Zinc Chloride.) (Hydrogen.) 

In the latter case it requires two molecules of the acid 
to combine with one of zinc, forming a molecule of zinc 
chloride and liberating two atoms of hydrogen. 

Acids, Bases, and Salts. — There are three general classes 
of substances with which we must become acquainted 
in order to understand the chemical principles of agri- 
culture. 

They are called acids, bases, and salts. 

The acids are a class of substances which generally 
have a sour taste. Vinegar contains acetic acid. 

Some of the more common acids are : sulphuric acid 



THE SUBSTANCES OF THE EARTH. 13 

(H2SO4), muriatic or hydrochloric acid (HCl), phospho- 
ric acid (H3PO4), sihcic acid (H4Si04), carbonic acid 
(CO,), nitric acid (HNO.), etc. 

Bases are a class of substances whose nature is very 
different from that of acids. A portion of them are 
called alkalies, or alkaline substances, and have a hot, 
sharp taste. 

Some of the bases are potash (K2O), sodium (Na), 
lime (CaO), magnesia (MgO), oxide of iron or iron rust 
(FeO), etc. 

Acids and bases have a strong attraction for one an- 
other, and when united form a class of substances called 
salts. They are so named because many of them have a 
taste similar to that of common salt. 

They are called sulphates, chlorates, phosphates, 
etc., as chlorate of potash (KCIO.,), phosphate of lime 
(CaOPPs), nitrate of soda (NaNOg), etc. 

Gypsum, or land plaster, is sulphate of lime and water. 
It is the result of a combination of sulphuric acid and 
quicklime : 

H2SO4 + CaO = (CaSO^ + H,0). 

Phosphate of lime is produced by a union of phosphoric 
acid and quicklime : 

2 H3PO4 + CaO = CaOP^Os + 3 H^O. 

If a feather is dipped in hydrochloric acid and held 
over an open bottle of ammonia, the ammonia, escaping 
by evaporation, will unite with the acid and form a white 
powder upon the feather, called ammonic chloride : 

NH3 + HCl = NH4CI. 

When the two parts of a rochelle powder are dissolved 
and poured together, the acid of the one unites with the 
base of the other, producing a salt, which remains dis- 



14 THE PRINCIPLES OF AGRICULTURE. 



1—^ 



solved in the water ; and carbonic acid, which escapes in 
the form of a gas, causing the effervescence. 

Cohesion and Adhesion. — As atoms have attractions 
which cause them to unite in molecules, so the molecules 
themselves have similar attractions for one another. 

When the attraction is between molecules of the same 
kind, it is called cohesion ; when between molecules of 
different kinds, it is called adhesion. 

Molecules of water have an attraction of cohesion for 
one another, but the adhesion between water and glass is 
sufficient to overcome this, and to cause a piece of glass 
to be moistened when dipped in water. On the other 
hand, an oily stick will not be moistened by water, be- 
cause the cohesion in water is stronger than the adhesion 
between water and oil. 

The adhesive attraction of water for gases causes the 
moisture of the atmosphere to absorb impurities and 
bring them down with the rain. 

The attraction of charcoal for various substances 
renders it useful as a filter for cleansing water, refining 
sugar, etc. 

In order that the forces of cohesion and adhesion may 
act, it is necessary to bring the molecules very near to 
one another. In breaking a piece of iron, we exert a 
force upon it sufficient to pull its molecules so far apart 
that the force of cohesion no longer acts. 

In order to weld the separated parts it is necessary to 
heat them until their molecules will move more easily, 
and then beat them together by hammering until the 
molecules are again brought within the range of cohesive 
force. 

In stretching a piece of rubber, we draw the molecules 
farther and farther apart, until finally the force applied 



THE SUBSTANCES OF THE EARTH. 



15 



is sufficient to overcome the force of cohesion by which 
the molecules are attracted to one another, and they are 
separated or the rubber is broken. 

The Porosity of Matter. — All matter is more or less 
porous. This is not only true of loose substances like 
soil, but also of more solid substances, like wood and 
iron. The pores in the latter are, like atoms and mole- 
cules, too small to be seen. 

B c w 

r 








Cross-section of Wood, magnified, showing Pores. 

B, the hark ; C, the cambium layer ', W, wood. 

It is believed that neither atoms nor molecules ever 
remain in absolute contact with each other, but that there 
arc always spaces between them. Through these spaces 
atoms and molecules of other substances are able to pass. 

A certain amount of salt and sugar may be dissolved 
in water without increasing the volume of water. The 
molecules of salt and sugar occupy the vacant spaces 
between the molecules of water. 

Under heavy pressure water has been forced through 
the pores of iron. A piece of iron may be made smaller 
by hammering. Its molecules are then driven nearer 
together. 

A bottle filled with gas will hold as much of another 
kind of gas as if it were empty. 



16 THE PRINCIPLES OF AGRICULTURE. 

^-^ Solids, Liquids, and Gases. — Matter exists in one of three 
states : either as a solid, a liquid, or a gas. The same 
substance may assume one of these forms at one time, 
and another at another time. 

The state is supposed to depend upon the degree of 
attraction by which its molecules are bound together. 

When they are firmly united, the substance is a solid. 
When the force that binds them is weaker, allowing them 
to move freely upon one another, it becomes a liquid. 
When the force is entirely overcome, it becomes a vapor 
or gas. The molecules then fly apart, tending to occupy 
as much space as possible. 

The state of a substance is partly dependent upon the 
temperature. 

Heat tends to overcome the attraction, and so to change 
a substance to the liquid or gaseous form. A moderate 
amount of heat will change a block of ice, first to water 
and then to vapor. A higher temperature will produce 
a similar effect upon other solids. 

Heat, by overcoming the force that draws molecules 
together, increases the distance between them, and so 
increases the space which they occupy and the size of 
the body. So, on the other hand, a low temperature al- 
lows the molecules to come nearer together, and renders 
the body smaller. 

There are a few exceptions to the general rule that 
heat expands and cold contracts. When water is cooled 
enough to freeze, or become a solid, it is crystallized ; 
that is to say, its molecules arrange themselves in cer- 
tain forms which require more space than if they were 
packed closely together. Tlie same is true of a few other 
substances when changing from the liquid to the solid 
state. 



THE SUisSTANCES OF THE EARTH. 17 

The expansive force of water in freezing, or crystal- 
lising, is very great. A pitcher filled with water, and 
allowed to freeze, is sure to be broken. The moisture of 
the soil in freezing beneath a building lifts it perceptibly 
every winter. 

Snowflakes illustrate the tendency of freezing water 
to crystallize. When examined with a microscope, they 
present a great variety of regular forms whose beauty 
and accuracy it would be difficult to imitate. 




Snow Crystals. 

Other substances, like sugar, salt, and alum, show the 
same tendency. When these are dissolved in water, as 
their molecules slowly come together again by the evap- 
oration of the water, they tend to arrange themselves in 
regular forms. 

Organic and Inorganic Matter. — Matter is sometimes 
divided into two classes : organic and inorganic. 

Wins. Agr. — 2 



18 THE PRINCIPLES OF AGRICULTURE. 

Organic substances are those which have been con- 
verted into living organisms ; or, in other words, which 
either form or have formed a part of the bodies of 
plants and animals. They are produced by the processes 
of life. All other matter is called inorganic. 

When organic matter is burned or decays, it returns 
again to an inorganic condition. 

Pieces of stone or iron, for instance, are not organic, 
because they have no organs such as exist in anything 
which has life. On the other hand, wood, hay, flesh, 
and bones are examples of organic matter, since they 
have been produced by the growth of living plants and 
animals, and retain the same matter and the same form 
which they had when in a living state. Soil may be 
partly organic and parti}' inorganic, since it not only 
contains mineral matter, but also vegetable and animal 
matter, left by the death of plants and animals, which 
has not yet become so far changed as to lose its organic 
condition. 

Organic substances have never been produced by arti- 
ficial means. For articles of food, — fruit, vegetables, 
and meat, — as well as for the materials used for cloth- 
ing, — cotton, wool, linen, and sillv, — the world must 
depend upon nature's processes in agriculture. 

All attempts to imitate nature by producing these sub- 
stances have failed. rsj 

Combustible and Incombustible Matter. — When any sub- 
stance is burned, some of its elements escape into the 
atmosphere in the form of gases and floating particles, 
and the remainder become ashes. The carbon unites 
with the oxygen of the air, and escapes as carbonic acid 
gas. Some of the nitrogen is converted into ammonia 
gas. The water is converted into vanor. 



THE SUBSTANCES OF THE EARTH. 19 

The elements which escape include the carbon, hydro- 
gen, oxygen, and nitrogen, and sometimes the sulphur. 
The remaining elements are found in the ashes. The 
former are called comhustihle or volatile^ and the latter 
incombustible or fixed. 

The following is a brief description of the more com- 
mon elements : — 

Oxygen is the most common and interesting of the 
elements. It forms about one half of the solid parts of 
the earth, eight ninths, by weight, of all water, and one 
fifth of the air. It has powerful attractions for many 
other elements. The substances formed by its union 
with these are generally called oxides. Water (HgO) 
is sometimes called hydric oxide. Lime (CaO) is cal- 
cic oxide; iron rust (FeO), ferric oxide. There are 
three familiar processes in nature in which oxygen 
takes a leading part : — 

1. Combustion. — The ordinary process of burning, or 
combustion, consists of the union of the oxygen of the 
air with carbon and some other elements of the fueL 
This union with carbon produces a gas (CO2) called 
carbon dioxide, or carbonic acid gas. 

Heat is a result of the union. It is regarded as a 
kind of force. The force or clash with which atoms 
come together in burning is converted into another kind 
of force called heat. The degree of heat depends upon 
the rapidity of the process. A draft through a fire in- 
creases the heat, because it furnishes a larger supply of 
oxygen. 

2. Oxidation. — In the rusting of metals, and the de- 
cay of wood, a process is going on precisely similar to 
that of burning, except that it is much slower. New 
combinations are formed, and the same amount of heat 



V 



20 THE PRmCU^LES OF AGRICULTURE. 

is produced as if the iron or wood were burned, or oxi- 
dized more rapidly. Tlie process is so slow that the 
heat is not noticeable. 

The decomposition and decay of all substances, in gen- 
eral, is largely a process of oxidation. Articles of food 
are preserved from decay by separation from the oxygen 
of the air. The decay of soft vegetable substance, as well 
as the crumbling of the hardest rock, shows the power 
of oxygen in transforming the products of nature. 

3. Respiration. — Respiration or breathing in animals 
is similar to combustion and oxidation. The oxygen of 
the air, taken into the lungs, enters the blood, where it 
unites with carbon. The carbonic acid gas thus pro- 
duced escapes with the breath into the atmosphere. 

The heat which results from this union serves to keep 
up the temperature of the body of the animal. The 
amount of heat per day produced in the system of a man 
by breathing is about equal to that obtained by burning 
a pound of coal. 

Plants breathe to a slight extent, taking in oxygen 
through the pores of their leaves, and giving off carbonic 
acid gas- 1 

-"--Hy^fSg^ is the lightest substance known. It weighs 
only one sixteenth as much as oxygen. It combines 
most readily with oxygen and chlorine. When burned 
or combined with oxygen, it forms water. It is an es- 
sential part of plants and animals. It is produced by the 
decay of animal and vegetable matter, or from molecules 
of water, by separating it from the atoms of oxygen- 
Nitrogen, in a free state, forms four fifths of the air. 
It is an odorless and harmless gas. Its purpose in the 
air seems to be to dilute the oxygen with which it is 
mixed and diminish its force. 



THE SUBSTANCES OF THE ExYRTH. 21 

It forms an essential part of plants and animals, and 
is of great importance for agricultural purposes. Its 
force of attraction for other elements is very weak. This 
fact increases the difficulty of retaining it in permanent 
forms. It is the most expensive part of fertilizers. 
With hydrogen it forms ammonia (NH3) ; with hydrogen 
and oxygen, nitric acid (HNO3). These are the two 
forms in which nitrogen most commonly becomes a 
source of fertility, and of importance in agriculture. 

Carbon is found in nature in three forms : as charcoal 
and similar substances ; as graphite, which is used in 
making lead pencils ; and as diamonds, which are simply 
crystallized carbon. 

It forms a large part of all animal and vegetable sub- 
stances. Coal, wood, and woody substances are largely 
composed of it. It is the element which gives value to 
substances used as fuel. 

Charcoal, which is largely composed of free carbon, is 
produced by burning wood in a partially smothered fire. 
The process releases the carbon from other elements 
with which it is combined, and retains it by excluding 
the oxygen of the air, with which it would otherwise 
unite and escape as carbonic acid gas. 

If a piece of wood is placed in sulphuric acid and al- 
loAved to remain for some time it becomes black. The 
acid removes the other elements of the wood and leaves 
the carbon. 

If a piece of glass is held over the flame of a candle it 
becomes " smoked," or covered with minute particles of 
carbon, which escape faster than they can be consumed. 

All plants contain a large proportion of carbon. In 
cotton fiber it is almost pure. Sugar, which is a product 
of plants, is forty-two per cent, carbon, by weight. 



22 THE PRmCIPLES OF AGRICULTURE. 

Silicon is the most abundant solid substance known. 
It forms about one fourth of the solid parts of the earth. 
It is commonly combined with oxygen in the form of sil- 
ica (Si02). Quartz rock is a variety of silica. It forms a 
large part of granite rock, sandstone, and common sand. 
It serves, like an acid, to unite with bases, forming what 
are called silicates. Common glass is a mixture of dif- 
ferent silicates. Clay is chiefly composed of silicate of 
alumina. 

Silica is found in plants, particularly in the grasses. 
It gives to the stalks and branches greater firmness and 
hardness. 

Sulphur is a familiar substance, commonly known as 
brimstone, or flowers of sulphur. With hydrogen and 
oxygen it forms sulphuric acid (H2SO4), one of the most 
common acids. This acid forms a great variety of useful 
salts, as sulphate of potash (K2SO4), sulphate of lime 
(CaS04), etc. 

Sulphur is always found in plants and animals. The 
strong flavor of such vegetables as turnips and onions is 
due to the presence of sulphur. 

Phosphorus is a soft, yellow substance, which unites 
with the oxygen of the air and takes fire so easily that 
it can only be kept under water. It is used in manu- 
facturing matches. It combines with hydrogen and 
oxygen, forming phosphoric acid (H3PO4), a substance 
of great importance in fertilizers. It forms about ten 
per cent, of the bones of animals, in the form of calcium 
phosphate. 

Chlorine is a gas which is found only in combination 
with other elements. With hydrogen it produces hydro- 
chloric or muriatic acid ( HCl) ; with sadium, sodium 
chloride or common salt (NaCl). . 



/xy 



THE SUBSTANCES OF THE EARTH. 23 

Potassium is a soft, light substance, whose affinity for 
oxygen is so strong that it can only be kept pure in some 
substance containing no oxygen. When placed upon a 
piece of ice it burns freely. 

With oxygen it forms potash (K2O), and with oxygen 
and hydrogen caustic potash (KOH). Potash unites 
with acids producing a variety of salts of potash, as chlo- 
rate of potash (KCIO3), sulphate of potash (K2SO4), etc. 

Sodium is somewhat similar to potassium. It forms a 
great variety of salts, of which common salt (NaCl) is a 
familiar example. Caustic soda is prepared in large 
quantities for manufacturing soap. 

Calcium is a common substance, found in combination 
with other elements, from which it is not easily separated. 
In limestone and marble it is united with carbonic acid, 
forming calcium carbonate (CaCOg). 

Compounds of calcium constitute a large part of the 
shells of clams, oysters, and other shell-fish, and also of 
the bones of all animals. 

Magnesium is a metal found in some rocks. The pure 
metal burns brilliantly, and is sometimes used for illu- 
minating purposes when a very strong light is required. 
It is found to some extent in plants and animals. With 
oxygen it forms magnesia (MgO). 

Aluminium is somewhat similar to magnesium. It 
resembles silver in appearance. It is used to a small 
extent in making jewelry and ornamental work. The 
sapphire and ruby are beautiful forms of alumina. It 
exists largely in common clay in combination Avith silica. 

Iron is found in many parts of the earth in the form of 
ore, which is purified and used for manufacturing pur- 
poses. It exists to some extent in all soils. It gives 
clayey soils their dark brown color. 

i 



,'/ 



24 THE PRINCIPLES OF AGRICULTURE. 



QUESTIONS. 

How many different elementary substances are there in the earth? 
^Name those which are most common. Name as many others as 
you can think of. What is meant by the symbol of a substance ? 
Name the symbols of the most common substances. 

What is an atom ? Have atoms ever been seen ? How do we know 
that they exist? How are atoms represented? Give an idea 
of the size of an atom. Can an atom be divided? Can it be 
destroyed ? 

What is a molecule? What causes atoms to form molecules? How 
is a molecule represented ? How are the atoms of a molecule 
arranged ? 

Upon what does the nature of matter depend ? Must all substances 
composed of carbon, hydrogen, and oxygen be alike? Can the 
molecules of a body be broken or divided? How can this be done? 
What effect does this have upon a body ? AVhat would be the 
effect of making a different arrangement of the atoms in the mole- 
cules of a substance ? 

Wliat is chemical action ? Give an example of chemical action, and 
explain it. 

What are acids ? Bases? Salts? Name some of each. 

Give a chemical equation showing how bases are formed. 

What is cohesion ? What is adhesion ? Why does your hand become 
wet when dipped in water ? Why are the feet kept dry by greas- 
ing the boots ? How is water purified by leaching through char- 
coal ? Why are not two pieces of wood touching each other held 
together by cohesion ? 

How many porous substances are there? How do we know that iron 
is porous ? Why can salt be added to a glass full of water without 
causing it to run over? Why may two gases appear to occupy the 
same space at the same tmie ? 

Explain the difference beween solids, liquids, and gases? Why is a 
substance melted by heating it ? How is it that heat expands and 
cold contracts? Why does water expand in freezing? 

What is the difference between organic and inorganic matter? Is 
hay organic or inorganic ? A potato ? Water ? Milk ? Sand ? 
Ordinary soil? 



THE SUBSTANCES OF THE EARTH. 25 

Explain the difference between combustible and incombustible matter. 
Mention some common substances which are ])artly combustible. 
Mention some which are entirely combustible. Name some that 
are entirely incombustible. 

How much oxygen is there in the earth? What is an oxide? Ex- 
plain the process of burning. What is heat ? Why does a fire burn 
better in a draft of air ? Why has decayed wood lost a part of its 
value for fuel? Why do we seal fruit to preserve it? How does 
breathing keep the body warm ? 

What are the peculiarities of hydrogen ? Why is water produced by 
burning hydrogen ? Where is nitrogen to be found ? Why is it 
so difficult to obtain it for practical purposes ? 

Name some objects that contain carbon. What proportion of the 
earth is silicon ? Name some forms in which it is found. Name 
some of the uses of sulphur. Describe phosphorus. Name some 
useful forms of chlorine. 

Describe potassium. Name some of the salts of potash. Mention 
some useful forms of sodium Where is calcium found? How 
may magnesium be distinguished ? Name some forms of aluminium. 
Where does iron exist? 



CHAPTER 11. 

LAND AND WATER. 

The Former Condition of the Earth. — The earth has not 
always been as it now is, but has been gradually chang- 
ing through long periods of years. It is believed that 
it was once very hot, — so hot that all the solid sub- 
stances now upon it were melted, or converted into gases. 
As it gradually cooled upon the outside, some of these 
liquids and gases became solid, and formed a crust upon 
the surface. It is believed that the interior of the earth 
remains to the present day in a very hot condition. 
There are several indications of this : — 

1. In descending into the earth, after passing below 
the effect of the sun's heat, the temperature becomes 
higher the farther we descend. 

2. Earthquakes are, in some way, due to movements 
of the melted substances or gases, or of the crust above 
them. 

3. Some of the hot liquids and gases are often poured 
forth from volcanoes. 

It is hardly to be supposed that the whole of the 
earth's interior is a liquid, because, while the temper- 
ature may be sufficiently high to melt all known sub- 
stances, the immense pressure under which all matter is 
placed at any great depth below the surface must be 
sufficient to retain it in a solid form, notwithstanding 
the excessive heat. 

(26) 



LAND 4ND WATER. 27 

As the process of cooling went on, the moisture of the 
atmosphere became condensed ; and, falling as rain, cov- 
ered the earth's surface with water. 

Out of this primitive earth, this crust of mineral sub- 
stances, and the water and atmosphere surrounding it, 
and out of the plants and bodies of animals that have 
lived and died upon its surface, have been formed the 
soil and rocks of our present earth. 

The Age of the Earth. — The processes by which this 
great change has been brought about have been, for the 
most part, silent and gradual. Many of them are still 
going on. Our earth, with the variety of substances 
upon it, is not to be considered as a thing completed, but 
as constantly undergoing changes in the great workshop 
of Nature. 

The period of time that has elapsed since the first 
solid crust was formed must be exceedingly long. Some 
of the lowest estimates made by careful students have 
been from fifteen to twenty million years. 

Continents. — It is a common principle in nature that 
heating a body causes it to expand, and cooling causes 
it to contract, or become smaller. Now, it is impossible 
for a spherical body, with a solid surface, to become 
smaller without forming upon its surface dents and 
I'idges, or depressions and elevations. As the ancient 
earth became still cooler and smaller, after having first 
formed a crust, it was natural that tliis crust should be- 
come irregular in shape, producing low and high places. 
The water naturally sank into the lower places, leav- 
ing the elevated regions as continents. 

The continents that thus first appeared above water 
were very small, and gradually increased in size, extend- 
ing their coasts as the continued shrinking of the crust 




The Beginnings of North America. ( White indicates land. ) 




North America in the Secondary Era. ( Wldfe indicates land.) 
(20 



LAND AND WATER. 



29 



raised them more and more above the level of the water. 
The first appearance of the North American continent 
was in a small, angular section, extending from the Great 
Lakes northeast to Labrador, and northwest to the 
Arctic Ocean. 




North America in the Tertiary Era. {White indicates land.) 

Mountains and Hills. — The cooling and shrinking of the 
continent has also given rise to mountain ranges and 
valleys. The inward pressure and sinking of certain 
sections caused long cracks in the earth's crust, and the 
upturned edges have formed some of the great mountain 
ranges of the earth. 

Some mountains have also been formed by an accumu- 
lation of melted matter poured from these cracks and 
from volcanoes. 



ij^ 



30 THE PRINCIPLES OF AGRICULTURE. 

Many of the smaller hills have been formed by bodies 
of moving water and ice, which have ground out valleys 
between them. 

The formation of hills, and other changes upon the 
face of nature, have been brought about gradually. Fall- 
ing rains and running streams are slowly reducing the 
size of the hills by wearing them away and carrying them 
to the valleys below. In some cases, on the other hand, 
swift running streams and rivers are wearing out and 
increasing the depth of the valleys between the hills. 

The Soil — If we examine some soil with a microscope, 
we shall find that, while it contains some other sub- 
stances of a different nature, a large part of it is com- 
posed of finely divided particles of rock. These are 
generally of a similar nature to the larger rocks that 
are scattered through the soil, and have been produced 
from large rocks by the grinding and crumbling forces 
of nature. 

The greater part of our present soil, however, was not 
formed directly out of the original rocks of the first 
crust of the earth. The soil formed by the first crumb- 
ling of the original rocks generally solidified, or petri- 
fied, into rock again, and this process of crumbling and 
solidifying continued through several alternations until 
our present soil was formed. 

Nearly all the present rocks were at some time soil. 
Conglomerate stones, sometimes called "pudding-stones," 
are examples of an ancient soil, containing stones of 
different kinds, which has been transformed into solid 
rock. Sandstone was once a bed of sand. 

Specimens of rocks from the original crust are now to 
be found only in a few scattered localities in those sec- 
tions which first appeared above water, where, by virtue 



LAND AND WATER. 31 

of their elevated position, they have partly escaped the 
forces that would tend to destroy them. 

The process of rock-making is still going on. There 
is often to be found, beneath the surface soil, a stratum 
of " hard pan," through which it is difficult to penetrate. 
This is gradually becoming solidified by the action of 
chemical forces, and at some time in the distant future 
will become stone. 

The chief agencies in nature which have done the 
work of grinding rocks, and preparing the soil of the 
earth, are : — 

1. The Atmosphere. — Nearly all rocks, when exposed to 
the atmosphere above ground, undergo chemical changes 
upon their surface by which portions are continually 
crumbling and falling off. This effect upon some rocks 
will cause them to waste away in a very few years, while 
with others the process is much slower. 

Some varieties of sandstone are found near the surface, 
so much affected by the atmosphere, which has reached 
them through the porous soil, as to be easily crumbled 
into powder. 

The most enduring kinds of marble, used for erecting 
monuments, are generally covered with fine marble dust, 
showing that even they are not exempt from the uni- 
versal tendency. 

2. Running Water. — With every shower and rain 
storm, and with the melting snows in spring-time, 
streams and brooklets are constantly wearing away the 
rocks, and washing away soil from the sides of hills 
and mountains, and carrying it into the rivers below. 
As the current of the river becomes less rapid, this soil 
settles, forming deposits on the banks of the river at its 
mouth, or on the neighboring shores of the ocean. 



32 THE PRINCIPLES OF AGRICULTURE. 

When the streams and rivers are much swollen, they 
wash out and bear away many rocks in their swift cur- 
rent. As these are rolled and tumbled one upon an- 
other, they are ground into soil, which is added to the 
general deposit. The mountains and hills are thus grad- 
ually carried away to fill the valleys below^, and to extend 
the coasts of the continent. The rich alluvial lands in 
river valleys have been formed in this way. 

3. The Ocean. — The movements of water on the shores 
of the ocean produce an effect similar to that of rivers. 
The flow and ebb of the tide, and the breaking of waves 
on the beach, grind rocks into sand, or wash up shells 
from deeper water, grinding them into fine powder. This 
process has been going on since land first appeared above 
water, forming the origin of our continent. 

The ocean has been continually forming beds of sand 
and mud on or near its shores. These have been raised 
above the surface, as the waters have receded, and in 
many cases have become consolidated into rock. Sand- 
stone and limestone have been mostly produced in this 
manner, the former from the sand beds, and the latter 
from mud formed by the grinding of shells. A similar 
effect has been produced by large lakes, some of which 
have become entirely dry, leaving deposits of sand, lime, 
or other mineral matter. 

4. Ice. — Ice forming in the cracks and crevices of 
rocks, year after year, tends by its expansion to burst 
the rocks or open crevices, thus admitting the atmos- 
phere, and hastening the work of crumbling. 

Minute particles are also detached from the rocKs by 
the freezing and thawing of the moisture upon their 
surface. If a number of clean stones are placed in a 
pail of pure water, and the water is allowed to freeze 




(33) 



34 THE PRINCIPLES OF AGRICULTURE. 

and thaw several times, there will be found a perceptible 
quantity of fine particles at the bottom. 

But the greatest effect of ice in forming soil, and 
changing the face of nature, has been through glaciers. 

In high, mountainous regions, and in cold latitudes, 
snow steadily accumulates, forming immense masses of 
ice in the deep valleys. These are steadily, but very 
slowly, pushed along by their own weight until they 
reach a lower and warmer region, where they melt away. 
These huge rivers of moving snow and ice are called 
glaciers. Rocks in the course of the glacier are torn up 
and borne along, grinding upon one another, and grind- 
ing paths through other solid beds of rock, until they 
are deposited as bowlders and soil at the point where 
the glacier melts. 

It is believed that, at some time in the history of the 
earth, the regions to the north of the equator became 
for a time much colder than at present, causing perpet- 
ual snow to fall upon large portions of North America 
and Europe, deep enough to bury most of the hills and 
mountains beneath vast, continuous glaciers. 

These glaciers, moving toward the equator, ground 
enormous quantities of rock into soil, and deposited it 
over a large extent of country, together with the rocks 
which remained unground. Huge bowlders, as well as 
smaller rocks, scattered over the country, may be traced 
back northward many miles, to their original bed. In 
New England they have been carried two or three hun- 
dred miles, and in the Mississippi Valley one thousand 
miles. Soil and rocks which have been transported in 
this way are called drift. 

5. Winds. — Winds have also taken some part in form- 
ing soil, and especially in changing its location. In 



LAND AND WATEK. 35 

some sandy regions, large rocks have been partly worn 
a\yay by the sand which has for centuries been blown 
across their surface. Whole hills have, in some in- 
stances, been thus worn away and deposited in other 
localities. —'I 

The Composition of Soil. — The soil of the earth may 
be considered as composed of four different classes of 
substances : — 

1. Finely/ Divided Particles of Mock. — Crumbled rock, 
or sand, constitutes the bulk of many varieties of soil. 
Even soft, peaty soil will be found, upon careful exam- 
ination, to contain a greater or less percentage of gritty 
substance. 

2. Decaying Vegetable Matter. — Nearly all kinds of 
soil contain more or less of a soft, pasty, dark-colored 
substance called humus, or vegetable mold. The grass, 
leaves, and falling trees, which are continually accumu- 
lating upon the surface of the soil, and are mixed with 
it by cultivation, furnish a perpetual source of this hu- 
mus. It forms a large part of the peaty soil found in 
low places. In peat or muck beds it is nearly pure. 

Peat, or swamp muck, is an accumulation of vegetable 
matter which has been formed through long periods of 
the ancient history of the earth. 

In low, marshy places, certain kinds of rank vegeta- 
tion have grown year by year, or from age to age, and, 
falling, have been buried one upon another in water and 
mud. These accumulations have undergone a process of 
slow decay, or smothered combustion, under water, which 
has reduced them to a uniform mass of black or brown 
matter. The dark color is due to the presence of carbon 
which results from the slow combustion, as charcoal is 
obtained from the smothered burning of wood. 




' a 



(36) 



LAND AND WATER. 37 

In some cases, in low places, the process has been 
continued further, until the peat has been petrified, or 
converted into coal. 

Peat beds are very numerous. Some of them are of 
very large extent. The great " Dismal Swamp " of Nortli 
Carolina is a vast peat bed. 

Many of the smaller muck swamps are partly com- 
posed of ordinary suil, which has been washed in from 
the surrounding hillsides. ^ 

3. The Remains of AnhnaU. — The bones and shells 
of all the great numbers and varieties of animals that 
have lived and died on the land, and in the ocean, 
have contributed to the formation of certain kinds of 
soil. Limestone, and limy matter in soil, have been 
produced from shells which have accumulated in the 
ocean, and in lakes which have become dry. The rock 
of coral reefs, and the soil formed by the crumbling of 
such rock, are largely composed of the remains of minute 
animals. 

The bones of land animals, when decomposed or 
ground, add desirable elements to the soil. 

4. Substances formed by Chemical Action from the 
three Classes mentioned. — The presence of these sub- 
stances gives fertility to the soil. Neither crumbled 
rock, nor the remains of plants or animals, in their 
crude original condition, would furnish any food for 
the support of plants ; but by chemical processes in the 
soil new combinations are gradually formed which are 
adapted to the support of vegetable life. 

Soils are commonly classified according to the sub- 
stances of whicli they appear to be largely composed, 
as follows : — ^K.y^^"'^'^ 

1. Sandy. — Pure sand, which is composed entirely 



38 THE PRINCIPLES OF AGRICULTURE. 

of particles of quartz rock, would be of little value for 
agricultural purposes. It can furnish no food for the 
support of plants. It is generally, however, mixed with 
other substances which give it some fertility. Sandy soil 
has but little power to retain moisture. Rain water 
readily soaks through it and runs away. Such land suf- 
fers severely from a drought. It is, furthermore, unable 
to retain for any length of time the supplies of plant 
food which are formed in it or added to it. These sub- 
stances are washed out as water passes through it. It is 
called light soil, and has the advantage of being easy to 
till. It becomes dry and warm enough for cultivation 
earlier in the spring than other kinds of soil. 

2. Gravelly. — Gravel is like sand, except that the 
rocks of which it is composed have not been ground 
so fine. Gravelly soil is largely composed of rocks 
ground to various degrees of fineness. It has the same 
general properties as sandy soil. When nearly pure, 
it is even less valuable than the latter for agricultural 
purposes. 

3. Clayey. — Clay consists of certain kinds of de- 
composed rock. Pure clay, of itself, contains but little 
plant food, but it possesses in a remarkable degree the 
property of absorbing and retaining other substances 
which tend to render it fertile. Fertilizers which have 
been applied to clayey soil are retained for a long time, 
until withdrawn by growing crops. 

Water leaching through such soil is found to come 
away as pure as when it enters, washing away no valu- 
able substances. 

It is called heavy soil. Water passes through it very 
slowly, so that it cannot be tilled until late in the spring, 
or for a lonsi: time after heavv rains. If handled and 



LAND AND WATER. 39 

pressed together when wet, it has the peculiar tendency 
to form hard lumps, requiring considerable labor to 
pulverize them and provide a fine seed-bed for crops. 

4. Peaty ^ or Mucky. — This is one of the most valu- 
able kinds of soil for agricultural purposes. It consists 
of a mixture of ordinary soil with large quantities of 
vegetable mold. It has great power to retain moisture 
through periods of diy weather. It contains large sup- 
plies of some kinds of plant food, which are gradually 
converted into suitable form to meet the demands of 
successive crops year after year. 

5. Limy^ or Calcareous, — Most soils contain some 
lime. In some cases the quantity is so large as to give a 
name to the soil. The variety of soil called marl con- 
tains large quantities of carbonate of lime. 

The lime in soil serves to some extent as food for 
plants, as all plants require a small quantity of it. It 
also serves a good purpose indh^ectly, as a base, by com- 
bining with acid substances in the soil, and forming salts 
which are desirable as plant food. 

6. Loam. — This is simply a general name applied to 
ordinary soil, which contains a mixture of the varieties 
mentioned, combined in varied proportions. If quite 
sandy, it is called sandy loam ; if quite clayey, clayey 
loam. 

QUESTIONS. 

What was the original condition of the earth ? How did the surface 
become solid ? What is the present condition of the interior of 
the earth ? How do we know it? What caused the appearance of 
water upon the earth ? How old is the earth ? 

How were the continents formed? Explain the origin of mountain 
ranges and hills. Of what is soil largely composed? How has it 
been formed? Give the history of most of our present rocks. 



40 THE PRINCIPLES OF AGRICULTURE. 

Is any of the first crust of the earth still in existence ? Name the 
five natural agencies that have ground rocks into soil. 

What is the effect of the atmosphere ? What work do streams and 
rivers perform ? What has the ocean done ? Explain the eft'ect 
of ice upon rocks in winter. What is a glacier ? Where are gla- 
ciers to be found at the present time? How have glaciers assisted 
in forming soil? What has been the effect of winds? 

Name the classes of substances of which soil is composed. Explain 
the origin of humus, or vegetable mold. Give the history of the 
formation of peat beds. What is the origin of limestone ? Name 
the different varieties of soil. Give the peculiar properties of 
each. 



en AFTER III. 

THE ATMOSPHERE. 

'""pHE atmospliere includes the air and other gases 
L and vapors which surround the earth. Its com- 
position is as follows : — 

1. Air. — Air forms the bulk of the atmosphere. It 
is composed of oxygen and nitrogen, in the proportion 
of one part oxygen to four parts nitrogen. The two are 
not chemically united into molecules, but the molecules 
of each are thoroughly mixed together. It is the oxygen 
of the atmosphere that is essential to plant and animal 
life. The purpose of the nitrogen seems to be to dilute 
the oxygen and reduce its force. 

2. Water Vapor. — There is always present in the air, 
and distributed through it, more or less moisture, or 
vapor of water. The quantity varies from one fiftieth to 
one two-hundredth part of the bulk of the air. This 
moisture passes into the air by evaporation from the 
surface of bodies of water, from the surface of the land, 
and from all moist substances. 

We are reminded in various ways that the air contains 
moisture, as in the drops that form upon the outside of a 
pitcher of cold water, in the moisture that accumulates 
upon the window-pane and forms a thick covering of frost 
in winter and in the moisture that appears upon the 
grass in the morning. 

(41) 



42 THE PRINCIPLES OF AGRICULTUPvE. 

When the air becomes overcharged with moisture, the 
surplus comes to the earth again in the form of rain. 

3. Carbonic Acid Gas. — The chief sources of this gas 
in the atmosphere are the breathing of animals, the burn- 
ing of fuel, and the decay of organic matter. 

It is thrown off from th-e systems of animals as useless, 
but is essential to the life and gro\\:th of plants. 

It may be seen that the escaping breath contains car- 
bonic acid, by breathing through a tube into clear lime- 
water. There will be formed in the water a white 
powder, which is carbonate of lime, produced by the 
union of the carbonic acid and the lime. 

Although the air always contains some carbonic acid 
gas, when too large a quantity is present it becomes poi- 
sonous. For this reason it is unwholesome to sleep in 
a small, close room, without some ventilation, or for 
many persons to remain long in any closed room. The 
burning of lamps in a room, or the decay of vegetables 
in a cellar, produces the same effect as the breathing of 
persons, by adding to the proportionate amount of car- 
bonic acid gas. 

4. Impurities. — The air contains small quantities of 
various substances, as ammonia, nitric acid, etc., besides 
smoke and dust. 

These are largely absorbed by the water vapor, and 
brought to the earth in raindrops. They give rain-water 
its dark color, and render it of some value as a fertilizer 
for crops. 

Weight of the Atmosphere. — The atmosphere has weight 
as truly as the objects which we can see and handle. 
The height, or distance from the earth to which it ex- 
tends, is not definitely known. It is variously estimated 
at from one hundred to five hundred miles. 



THE ATMOSPHERE. 43 

It produces a pressure upon every spot equal to the 
weight of the whole column above. This pressure 
amounts to about fifteen pounds upon every square 
inch. 

The pressure is not simply upon the top of an object, 
but upon the sides and underneath as well. It is not 
like one solid body resting upon another. The particles 
of gases and liquids move about so freely that the pres- 
sure upon any object contained in them is evenly distrib- 
uted in every direction. 

As the pressure of the air is evenly balanced upon all 
sides, we are not conscious of it. 

Upon the outstretched hand there rests a column of 
air that would weigh two or three hundred pounds. We 
are not conscious of it, because there is an equivalent 
pressure underneath the hand to support it. When the 
pressure underneath is removed by placing the hand 
upon the receiver of an air-pump, and exhausting the 
air, the pressure upon the top becomes painful. If the 
moistened palms are rubbed closely together, so as par- 
tially to remove the air, some force is required to pull 
them apart. If the air is removed from the mouth by 
expanding the lungs, the pressure of air outside forces 
the cheeks inward. 

The atmosphere near the earth is more compressed 
and heavy than at some distance above it, because there 
is more air above to press down. There is a marked 
difference between the pressure and density of air in 
a valley and on a high mountain. 

The barometer is an instrument for determining the 
pressure of the air. It really consists of a tube sealed 
at one end, filled with mercury, and inverted into a cup 
or bag of mercury. The pressure of air upon the mer- 



44 



THE PRINCIPLES OF AGRICULTURE. 



cury in the cup or bag forces this up into the tube until 
the column of mercury in the tube is heavy enough to 
balance the pressure of the air. The heavier the air, 
the more it will press, and the higher the column will 

rise in the tube. On the 
other hand, the lighter the 
air, the lower the colunni 
will fall. 

Changes of temperature 
and movements in the atmos- 
phere cause the weight and 
pressure to vary. As this 
variation is correctly deter- 
mined by the barometer, this 
instrument becomes of great 
service in calculatnig proba- 
ble changes of weather. 
f^^y;;^Temperature. — The ther- 
^"''^mometer is used to deter- 
mine the temperature, or the 
amount of heat that the at- 
mosphere contains. It con- 
sists of a tube, with a bulb 
at the lower end, containing 
mercury or alcohol. On the 
principle that heat expands 
and cold contracts, when the atmosphere becomes warm 
the mercury or alcohol expands and rises in the tube, 
and as the atmosphere becomes cooler it contracts and 
falls. 

Winds. — Since the atmosphere is invisible, we are 
apt to forget that it exists, until reminded by the force 
of the wind that it is a real substance. Wind is simply 




A Barometer Tube. 



THE ATM(3SPHERE. 45 

air in motion. Its force depends upon the rate at which 
the air is moving, varying from a slight motion, which 
gives a gentle breeze, to a velocity of forty or fifty 
miles per hour, producing a hurricane, a tornado, or a 
whirlwind. 

Cause of Winds. — Winds are always caused by the 
unequal density or weight of different portions of the 
atmosphere. This is generally due to differences in tem- 
perature. It is true of the air, as of other substances, 
that heat expands it, making a given bulk of it lighter ; 
and that cold contracts it, making a given bulk heavier. 
If a quantity of oil is poured into a body of water, the 
water, which is heavier, will push the lighter oil to the 
surface. So, if the atmosphere in any locality becomes 
warmer and lighter than the surrounding atmosphere, 
the latter will push it into the upper regions, and will 
rush in to fill the space underneath. 

The high wind that accompanies a thunder-storm at 
the close of a hot day is due to the fact that the atmos- 
phere, which has been heated during the day, is now 
rapidly rising, while the cooler atmosphere around is 
rushing in. 

The land and sea breezes, which are common on the 
sea-coast, are due to the unequal heating of the atmos- 
phere over land and water at different times of day. 

Rain. — Rain is an accumulation of the vapor of the 
atmosphere into drops, which, by their weight, fall to the 
ground. There is a limit to the quantity of water which 
the air is capable of absorbing and retaining as an invis- 
ible vapor. When it contains as much as possible, it is 
said to be saturated. Now, warm air is able to hold more 
moisture than cold air ; hence, when air whicli is satu- 
rated becomes colder, for any reason, it can no longer 



46 THE PRINCIPLES OF AGRICULTURE. 

retain all its moisture. A portion is liberated, accu- 
mulates in drops, and falls to the earth. This is in 
all cases the explanation of rain. 

The different ways in which the air is cooled, and rain 
is produced, are : — 

1. By Rising into the Upper Regions. — The higher we 
ascend from the earth's surface, the cooler we find the 
atmosphere. Mountains are sometimes clothed with 
grass and flowers at the foot, while their summits are 
covered with perpetual snow. 

The atmosphere is warmed chiefly by the warm earth. 
The heat of the sun's rays is accumulated upon the 
surface of the earth. The earth then, like a heated 
stove, throws out or radiates its heat, and warms the 
atmosphere. So, as in case of the stove, the atmosphere 
nearest it is always the warmest. 

As the air in any locality becomes heated in this 
way, it is pressed upward by cooler and heavier air from 
other sections, where it is cooled ; and, if it contains 
sufficient moisture, rain is produced. 

Ascending air is also cooled by expanding. When air 
is compressed so as to occupy a smaller space, it becomes 
warmer. On the other hand, when air expands, it be- 
comes cooler. As the air ascends, the pressure upon it 
from the air above becomes less, and consequently it 
expands and becomes cooler. This, of itself, is a com- 
mon cause of rain. 

2. By Passing over Mountains. — Hills and mountains 
are sometimes called " rain condensers." As the rising 
currents of air pass over mountainous regions, the air ex- 
pands and is cooled, and parts with its surplus moisture. 
Hilly regions are more abundantly supplied with rain 
than level tracts. That side of a range of mountains 



THE ATMOSPHERE. 47 

which the wind reaches first in its customary course 
receives more rain than the opposite side, since the cur- 
rents of air lose moisture in passing over it. The absence 
of rain on some parts of the coast of South America is 
due to the fact that the wind, which blows constantly 
from the east in those regions, causes the atmosphere to 
deposit rain, and become comparatively dry in passing 
the Andes Mountains. 

3. By the Mixture of Warm and Cool Currents of 
Air. — In the changing courses of variable winds, warm 
currents of air often meet and mingle with cooler cur- 
rents. When the air is saturated, this is liable at any- 
time to cause rain. ^ '' J 

Snow and Hail. — Snow and hail are frozen forms of 
atmospheric moisture. In the case of snow, the minute 
particles of moisture are frozen as they form, and arrange 
themselves about each other in beautiful crystals, pro- 
ducing the snowflake. 

Hailstones are often formed by whirling currents of 
wind, which carry raindrops or minute snowballs first 
into the upper, cold regions, where they are frozen, 
then downward through a warmer section, where more 
water is added, and then upward again. The size of the 
stones is thus gradually increased until they become too 
heavy to be carried upward again, and are flung to the 
earth. 

Fogs, Mists, and Clouds. — These are all of the same 
nature. They are simply particles of water or ice which 
have formed at points where currents of air of different 
temperatures meet each other, but not in sufficient quan- 
tity to produce raindrops. 

Clouds are formed wherever the air, in rising, is cooled 
enough to condense vapors. When the air is quite dry, 



48 THE PRINCIPLES OF AGRICULTURE. 

clouds will not be formed until a high point is reached, 
if at all. When it is well saturated, they may be formed 
so low as to touch the earth, and are then called fogs or 
mists. 

Dew. — Dew, like rain, fog, etc., is caused by the cool- 
ing of the atmosphere. The earth during the night be- 
comes cooler than the air above it, and tends to condense 
moisture from the air which comes in contact with it. 

Til ere is less dew on a cloudy night, because clouds 
prevent the earth from cooling. They obstruct the rays 
of heat as these pass from the earth, and turn them 
back, thus preserving an equality of temperature be- 
tween the earth and the air. 

A strong wind prevents the formation of dew by keep- 
ing the air well mixed, and leaving no part of it in con- 
tact with the ground long enough to become cool and 
deposit moisture. 

A slight breeze increases the amount of dew by 
removing those portions of air which have already 
deposited their moisture, and bringing other portions 
successively in contact with the ground. 

The quantity of water that forms upon the ground as 
dew is much larger than is generally supposed. It is 
only a portion of it that appears in the morning on the 
blades of grass. A large part is absorbed into the soil. 

In Great Britain, where dews are heavy, it is esti- 
mated that the whole amount deposited in a year would 
be equal to a depth of several inches of water. In some 
tropical regions it is deposited so fast as to be equal to a 
light rain. 

Frost. — Frost is simply frozen moisture from the at- 
mosphere. When the temperature at the point where 
dew would form falls below 32°, the point at which water 



THE ATMOSPHERE. 



49 



freezes, the moisture condensed from the air, instead of 
forming dew, forms crystals of ice, or frost. 

When there is no dew, there can be no frost of this 
kind, and vegetation is not injured unless the temper- 
ature falls low enough, and remains low long enough to 
freeze the sap within the plant. 




. Isobars, every -^aths of an inch difference 

of pressure. 

Isotherms, every 10 degrees temperature. 

• Low " = Center of Cyclone. 
■ High " = Anticyclones. 

>^ 



Direction of ivind cfc clear weather 
" " " " cloudy " 

" " " " rain. 

" " " " snoiv. 



V- path of Cyclone. 

"Weather Map. 

The Weather. — The changes of weather whicli are con- 
stantly taking place are not irregular and accidental. 
They occur according to certain laws, and as the result 
of certain causes. By ascertaining these causes, it is 
possible to predict changes, so that a storm, or a cold or 
warm wave of temperature, may be foretold some hours 

before it appears. 
Wins. Ag. — 4. 



50 THE PRINCIPLES OF AGRICULTUPE. 

The provision made by the United States for noting 
conditions, and announcing indications, in all parfs of 
the country, is of great importance. It is of great value 
in agriculture. The farmer, relying upon these indica- 
tions, may select favorable weather for planting his seed 
or harvesting his crops. 

Storms. — The central section of a storm is noted by 
an area of low barometer, or low pressure. That is 
to say, it is where the atmosphere is lighter than 
usual, and on that account is rising. In front and in 
the rear of the storm centej", the barometer is high, or 
the atmosphere is heavy. In the United States, these 
sections of low pressure, which mark the location of 
storms, are generally long and narrow, extending 
across the country from north to south. Storms usu- 
ally appear first in the western or southern parts of 
the country, and move in an easterly or northeasterly 
direction. 

Naturally, the winds on both sides of the storm center 
blow toward it. They are the heavier sections of air 
passing in to take the place of the lighter sections, which 
are rising ; hence, storms are generally preceded by east, 
northeast, or southeast winds, and followed by west, 
northwest, or "southwest winds. 

Climate. — The climate of a region is its condition with 
regard to heat and moisture. It may be considered a hot 
or cold, a moist or dry climate. 

The temperature in any locality depends chiefly upon 
the following conditions : — 

1. Latitude. — The extent to which the earth and the 
atmosphere near it become heated depends upon the di- 
rectness with which the rays of heat from the sun fall 
upon it. Sections near the poles are therefore colder 



THE ATMOSPHERE. 51 

than those near the equator, which have the sun more 
directly overhead. 

2. Elevation. — As the atmosphere is cooler the higher 
we ascend, so the climate of elevated tracts is colder than 
that of low plains and valleys. Although the high re- 
gions receive the full benefit of the sun's heat, they lose 
heat rapidly, since the atmosphere in these regions, be- 
ing thin and dry, permits the heat to pass off easily by 
radiation. 

3. Nearness to the Ocean, — The tendency of the ocean 
is to render the climate uniform, — cooler in summer 
and milder in winter. As the water upon the surface of 
the ocean becomes heated by the sun, it mingles with 
the cooler water below. This prevents the surface water 
from becoming very warm, and from imparting heat rap- 
idly to the atmosphere. 

As the ocean has stored a large amount of heat, and 
has become heated to a considerable depth, it is not 
quickly cooled as winter approaches, but parts with its 
warmth gradually during the entire winter. 

The solid land, on the other hand, does not become 
heated to a great depth. The heat of the sun is concen- 
trated upon its surface, and is more readily radiated into 
the atmosphere. 

In the fall of the year the ground is more quickly 
cooled, and has less influence in tempering the severity 
of winter. 

Near the coast, the climate is rendered comparatively 
uniform by receiving the benefit of cool winds from the 
sea in summer and mild winds in winter. 

The amount of moisture depends mostly upon the 
nature of the surroundings and the direction of prevalent 
winds. 



52 THE PRINCIPLES OF AGRICULTURE. 

Hilly and mountainous regions, which the winds reach 
first in their usual coarse, are generally well supplied, 
while more level regions farther on have a drier climate. 



QUESTIONS. 

Of what is the atmosphere composed ? What are the two elements of 
ah' ? Which of them is the more important V Of what use is nitro- 
gen in the air ? How much water vapor does the air contain ? Where 
does the air get it ? What becomes of it when there is more than the 
air can hold ? In what three ways is the carbonic acid gas of the 
atmosphere formed ? Name some of the impurities found in the 
atmosphere. AVliat finally becomes of tliese ? 

How much does the atmosphere weigli ? Why is its pressure greater 
in a valley than on a mountain? Is the atmosphere heavier or 
hghter in stormy weather ? 

AVliat is a barometer ? Wliy does the barometer fall before a storm ? 
In which direction does the atmosphere press? How many pounds 
of air rest upon your outstretched hand ? How are you able to lift 
so great a weight ? 

What is a thermometer ? What causes the mercury to rise and fall 
in a thermometer ? 

What is the wind ? What causes the wind to blow ? Describe the 
direction of the currents of air in a room with a hot stove at one 
side. What causes a sea breeze in a hot day on the coast ? Why 
is a thunder-shower usually accompanied by wind ? 

What is rain ? In what three ways is rain produced ? Why is the 
air always warmer near the earth than away from it ? Why are 
hills and mountains cooler than low places ? Why is there gener- 
ally an abundance of rain on that side of a mountain range from 
which the wind l)lows ? 

What is snow? Explain the formation of hailstones. Why does it 
sometimes hail when the temperature is below the freezing point V 
How can it snow when the temperature is above freezing ? 

What are fogs, mists, and clouds ? What determines the height of 
clouds? Why is it always cloudy before it rains ? 

Explain the cause of dew. How do clouds prevent the formation of 
dew ? Why is there no dew upon a windy night ? What is the 



THE ATMOSPHERE. 53 

effect of a slight breeze ? Give some idea of the quantity of dew. 
What causes ch-ops of water to form upon a pitcher of cold water 
on a hot day V 

What is frost ? When is frost liable to occur, and when not ? Upon 
which side of a window does frost form? Why is there less frost 
on the windows of a vacant room than on those of a room full of 
people ? 

Are the changes of weather accidental ? What is the work of the 
Weather Bureau, established by the government? Of what ad- 
vantage is it to the farmer? What is the general cause of a 
storm ? Describe the general course of storms in the United States. 
Which way do the winds naturally blow at the time of a storm, 
and why? 

What is meant by climate ? What three general conditions deter- 
mine the temperature of a locality ? Why is the temperature over 
the ocean more uniform than over the land ? AVhy are winiers 
usually most severe in the center of a continent ? What generally 
determines the amount of rain in any locality? 



CHAPTER IV. 



PLANTS. 

Seeds. — The growth of a plant begins with the seed. 
A seed contains all the essential parts of the plant it- 
self, ready to be extended outward into the soil and into 
the atmosphere as soon as favorable conditions are sup- 
plied. This minute plant found in the seed is called the 
" embryo," or " germ." 

Besides the germ, a seed contains a quantity of food, 
stored up to supply the young plant as it begins to grow, 

until it is able to pro- 
vide for itself from 
the soil and the at- 
mosphere. 

In the "chit" of a 
kernel of corn, and at 
the " eye " of a bean, 
the embryo is to be 
found. The remainder of the seed is composed of 
starch and other substances for the young plant to 
feed upon. 

The Vitality of Seeds. — Different varieties of seeds dif- 
fer greatly in the length of time they maintain their 
vitality, or power to sprout and produce growth. The 
seeds of some trees will not sprout at all after once be- 
coming dry. On the other hand, some seeds, if kept 
dry, will grow after many years. When sealed away 
from the air, these seem to retain their vitality almost 

(54) 




Sections of a Grain of Corn, and the Germ 
detached. 



PLANTS. 6,N 

indefinitely. Peas are said to have sprouted which 
were taken from an Egyptian mummy three thousand 
years old. 

It is better to select new seeds for planting. Older 
seeds may grow, but will generally produce weaker 
plants. 

Unripe Seeds. — Seeds used for planting should always 
be thoroughly ripe. The loss from planting unripe corn, 
or " pinched " wheat, may be many times as great as the 
extra cost of better seeds. 

While the difference in yield resulting from poor seeds 
may not always be apparent the first season, if the prac- 
tice is continued through a number of years the crop 
will " run out " and become unprofitable. 

On the other hand, by selecting the best specimens of 
seeds, year after year, the crop will be greatly improved. 
The yield of different crops has, in some instances, been 
doubled by a continuous selection of the best seeds. 

Conditions of Growth. — There are three conditions re- 
quired for the growth of seeds, all of which must be sup- 
phed in order to produce germination. 

1. Moisture. — When a dry seed is placed in soil, or 
some other moist substance, it immediately begins to 
absorb moisture ; it swells, and if the temperature is 
favorable and sufficient air is supplied, it puts forth its 
root, and begins to grow. 

The amount of moisture favorable for growth varies 
with different seeds. Some varieties will grow in water, 
some thrive best in very moist soil, while others require 
comparatively dry soil. 

It is believed that some varieties of seeds are covered 
with a coating through which water cannot penetrate, 
and that these may remain in the soil for an indefinite 



56 THE PRINCIPLES OF AGRICULTURE. 

period without germinating, until the hull is accidentally 
scratched, or broken, so as to admit moisture. This may 
account for the fact that so many weeds unexpectedly 
and repeatedly spring up after the soil is stirred in cul- 
tivating crops. 

2. Warmth. — There is a certain range of temperature 
within which a seed will grow, and outside of which it 
will fail to do so. 

The seeds of some plants, whose native home is in cold 
climates, will sprout at a low temperature, while others, 
which are accustomed to a warmer climate, require a 
higher temperature. The lowest point of temperature at 
which wheat, barley, oats, and peas will sprout is about 
40°, and the highest about 103°. The lowest for corn 
and squashes is about 50°, and the highest about 115°. 

Although the seeds may sprout at any point within 
this range of temperature, at a point near either extreme 
growth will be very slow, and the plants weak and small. 
There is a certain degree of heat for each variety of 
seeds in which they will produce the best growth. That 
point for wheat, oats, and barley is about 84°, and for 
corn and squashes about 94°. The nearer we approach 
to this favorable point in choosing the land and the 
time for planting, the better the results. The mistake 
is often made of planting seeds too early in the spring, 
before the ground is sufficiently warm to insure quick 
and strong growth. The early plant is so weakened 
by low temperature as to gain nothing in the end over 
the later plant, which thrives better, and yields larger 
results. 

3. Oxygen. — Oxygen, which is essential to support 
life in animals, being taken into their systems through 
the air in their lungs, is also essential to the life and 



PLANTS, 57 

growth of plants, and even to the sprouting of seeds. 
Soil is always more or less porous near its surface, and 
it is filled with air, which supplies the sprouting seed 
with oxygen, r^xl) 

Depth of Planting. — Most seeds would sprout and grow 
if dropped upon the surface of the soil in a rainy season, 
when the atmosphere is damp enough to supply the 
needed moisture, but it is generally safer and better to 
cover them with soil. 

The proper depth of planting will depend upon the 
nature of the soil, climate, crop, etc. In very wet or 
cold seasons, it is better to cover the seed but little, so 
that it may have better access to the air and the warmth 
of the sun. In warm, dry seasons, it should be buried 
more deeply, so as to secure sufficient moisture. 

In some sections of the country, and in some special 
seasons, Indian corn will thrive best when planted at a 
depth of several inches, while ordinarily a light covering 
is better. 

Many kinds of seeds will not grow at all if buried 
deeply. The seeds of weeds remain dormant in the soil, 
until they are brought near the surface by plowing or 
harrowing, where sufficient air and heat are supplied, 
and then they spring up and grow vigorously. 

Seeds are supposed to contain a supply of nourishment 
sufficient to support the young plant until the ascending 
stem can reach the open air. 

In some cases of deep planting, while there may be 
oxygen enough to produce growth, the supply of food in 
the seed becomes exhausted before the surface is reached, 
and the plant perishes. 

Germination. — The process of germination, or sprout- 
ing of seeds, includes three points. 



58 THE PRINCn^LES OF AGRICULTURE. 

1. The Absorption of Moisture. — It is evident that 
the nutritive substances contained in tlie seed cannot 
pass into the plant and support growth while in a dry 
state. The seed must be saturated with moisture, so that 
there may be a medium through which these substances 
may pass to the point in the growing plant where they 
are needed. 

2. A Change in the Nutritive Substances. — The sup- 
plies of food stored in the seed are not generally in a 
suitable form to support the plant, but must first be 
changed. They are dissolved in the moisture, and con- 
verted by chemical processes into the proper forms. An 
instance of this is the conversion of starch into sugar. 
The formula for starch is CgHioOj, and for the glucose 
sugar obtained from it, CeHioOe. The latter is obtained 
from the former by the addition of oxygen and hydrogen. 

In the process of malting barley and other kinds of 
grain, the aim is to obtain these same chemical changes. 
The grain is soaked and allowed to sprout until the 
starch and other substances are converted into sugar, 
dextrine, etc. The process is then stopped by drying, 
and the new substances are extracted from the gram to 
form malt. 

3. The Production of Heat. — The changes above re- 
ferred to are largely due to oxidation, or the combina- 
tion of oxygen with the substances of the seed. This, 
as in other instances of oxidation; produces heat. 

If a large number of seeds are heaped together, as in 
manufacturing malt, the mass becomes very warm, — so 
much so that care is required to prevent the grain from 
spoiling. This heat, developed in the sprouting seed, is 
of some service at times when the temperature outside 
is too low. 



PLANTS. 



59 



Growth from the Seed. — From the seed first appears a 
shoot, called the radicle^ which extends downward into 
the soil, and shortly afterward another shoot, called the 
plumule, which seeks to find its way upward into the air 
and sunlight. The radicle is the origin of 
the roots of the plant, and the plumule the 
origin of the stem, with its branches and 
leaves. 

The reason why the root thus turns 
downward and the stem upward is an un- 
solved mystery. It cannot be due to any 
attractive force of light upon the stem, or 
any repelling force upon the root, as it hos 
been found that the same directions are 
followed when a seed is sprouted in the air, 
in absolute darkness. From this and from 
other habits of plants, it would seem that 
they are endowed with a kind of instinct, 
similar to the instincts of animals. Some 
plants always turn their leaves toward the 
sunlight, while others turn them away. 
Some flowers close in the afternoon and 
open in the early morning. These facts 
we cannot account for with certainty, in 
a scientific way, any more than we can ac- 
count for the very principle of life which causes the seed 
to begin to germinate and its growth to continue. 

Two Worlds for the Plant. — • A plant has two worlds, 
or feeding grounds : the atmospliere above and the soil 
beneath. One is as essential to the life and welfare of 
the plant as the other. As plants cannot live when their 
roots are witlidrawn from the soil, so also most plants 
will die if the portion above the surface is repeatedly cut 




Germination of 
Wheat. 

o, the grain, con- 
taining the. coty- 
ledon; c,phnnule; 
r, radicle. 



60 



THE PRINCIPLES OF AGRICULTURE. 



off. Out of the soil and the a,tmosphere they obtain the 
A food which sustains their life and growth. 
^^f^The Food of Plants. — If we analyze the substances of 
which a plant is composed, and ascertain the elements 
which it contains, we shall know exactly what food it re- 
quires, and what the soil and atmosphere must contain 
in order to afford proper nourishment. 

The following elements are found in all plants, and 
are essential to their growth : carbon, hydrogen, oxy- 
gen, nitrogen, sulphur, phosphorus, potassium, calcium, 
magnesium, and iron. Besides these, there are generally 

found sodium, silicon, 
chlorine, and traces 
of some other sub- 
stances. 

Food from the At- 
mosphere. — The food 
which plants obtain 
from the atmosphere 
is mostly carbon. The 
leaves absorb carbonic 
acid gas (CO2), and 
separate the carbon 
from the oxygen, re- 
taining the former 
and returning the lat- 
ter to the atmosphere. This carbon, combining with 
hydrogen and oxygen in the plant, is converted into 
starch, sugar, cellulose, etc., and thus enters into the 
structure of the plant. 

This process of absorbing and decomposing carbonic 
acid gas takes place only in sunlight. In some unknown 
way, the influence of the rays of light is required to 




The Under Side of a Leaf. 
{Magnified, showing Cells and Mouths, or Stomata.) 



PLANTS. 61 

effect the change. For this reason a continuation of 
dark, rainy weather is injurious to the growth of most 
phmts. In sucli weather they turn pale from the absence 
of coloring material, which requires the aid of sunlight 
for its formation. 

The air is admitted to the interior of a leaf through 
minute openings, or mouths, which generally exist in 
great numbers. Upon an ordinary apple leaf there may 
be found as many as 100,000 of these openings. 

Plants Purify the Air. — This absorption of carbonic 
acid, and liberation of oxygen are of the greatest impor- 
tance to animal life. 

In the lungs of men and other animals, oxygen from 
the air is continually absorbed into the blood, and in 
place of it carbonic acid gas passes from the lungs with 
the breath. An accumulation of this gas in the atmos- 
phere would soon become poisonous, but the danger is 
avoided, and the balance maintained, by the fact that all 
growing vegetation is constantly withdrawing carbon and 
setting oxygen free. It is estimated that an acre of 
forest trees will consume the carbonic acid produced 
by the breathing of fifteen men. 

In this way vegetable and animal life mutually benefit 
each other, each requiring and making use of that ele- 
ment which is rejected by the other. 

Do Plants Breathe ? — While plants are taking in car- 
bon and throwing out oxygen, they are at the same time, 
though only to a slight extent, doing exactly the reverse, — - 
taking in oxygen and throwing out carbonic acid. This 
is very similar to the act of breathing in animals. 

It would seem unnecessary for the plant to take these 
two seemingly opposite courses, but they are for entirely 
different purposes. 



62 THE TRINCIPLES OF AGRICULTURE. 

The process of breaking up the molecules of carbonic 
acid, and retaining the carbon, requires the aid of sun- 
light, and is really a process of feeding, or upbuilding the 
plant ; but the act of breathing, or taking oxygen from 
the air, goes on continuously through the night, and is a 
process of oxidation or slow burning and destruction of 
the plant. 

Absorption of Water. — But little water, if any, is ab- 
sorbed by leaves from the atmosphere. A drooping plant 
is quickly revived by watering, or by a shower of rain, 
not so much by absorbing moisture through its leaves as 
by the rapid passage of water into the stem and leaves 
through its roots. 

Nitrogen from the Air. — While free nitrogen constitutes 
four fifths of all the air, it has generally been believed 
that none of this is directly available for the use of 
plants. Recent investigations, however, show that cer- 
tain varieties of plants are probably able, in some way, 
to make direct use of atmospheric nitrogen. This seems 
to be especially true of the family of plants called legumi- 
nous, or pod-bearing plants. This family includes peas, 
beans, clover, lucern, etc. 

Ammonia, which exists in small quantities in the 
atmosphere, is partly composed of nitrogen, and it is 
thought the plant may obtain a little nitrogen by ab- 
sorbing this gas through its foliage. 

' Roots. — The purpose of the root is to give the plant 
support, holding it firmly in position ; to absorb nourish- 
ment from the soil; and, in the case of biennial plants, 
to store up a sui)ply of food to support the plant the 
second year. 

The radicle, or first root which descends into the soil 
from the seed, soon subdivides into a number of small 



PLANTS. 



68 



roots which extend in different directions, or sends out 
small branches on all sides. 

Sometimes the radicle continues to enlarge and grow- 
downward, forming what is called a tap-root, from which 
small fibers extend out into the soil. Clover, Canada 




The Roots of Plants. 

A, Erigenia, with Hiherous root. B, Buttercups, imth fibrous roots. C, White 

Clover, with long tap-root and branches. 



thistles, and oak trees, for example, generally have such 
a tap-root. The root crops, beets, turnips, carrots, etc., 
are simply an enlargement of the tap-root, which serves 
to store up food intended for the support of the plant the 
following season. 

The growth of roots consists mostly of lengthening by 
building on additions at the extremities. In this way the 
difficulty of moving the root through its entire length is 
avoided, and every part, as soon as formed, is left in 



64 



THE PUmCIPLES OE AGl^ICULTURE. 



undisturbed contact with the soil. In some cases the tip 
of the root is provided with a kind of cap, or shield, to 
protect it from injury as it forces its way through the 
soil. 

The Number and Extent of Roots. — The process of sub- 
dividing and multiplying small roots goes on to a greater 
extent than is generally supposed. 
Rich soil in the vicinity of the 
roots of some plants becomes com- 
pletely filled with hair-like root- 
lets. Sometimes these are so 
small as to require the aid of a 
microscope to detect them. 

When a plant is pulled from 
the soil, these fibers are mostly 
broken off, only the larger roots 
remaining attached to the stem. 

The entire length of all the 
roots of a plant is sometimes 
almost incredible. In the case of 
barley, oats, and wheat, growing 
in rich, mellow soil, it has been 
found that the total length of all 
the roots of one plant will amount to from one hundred 
to one hundred and fifty feet. 

Under favorable conditions, roots sometimes descend 
to a great depth. In deep, mellow soil, the roots of most 
agricultural plants reach a depth of several feet. The 
roots of Indian corn, which in common soil do not extend 
more than two or three feet below the surface, have been 
known to penetrate into the earth to a depth of fifteen 
feet. Clover roots have been traced to a depth of eight 
feet. 




Extremity of a Rootlet of 
Maple. 

Hairs and root-cop (a), magni- 
fied 50 diameters. 



PLANTS. 65 

Food from the Soil. — The only substances that plants 
obtain from the atmosphere are carbon, small quanti- 
ties of oxygen, and probably some nitrogen in the case of 
certain particular plants. All other nutritive substances, 
generally including nitrogen, must come from the soil. 

A plant obtains these nourishing substances from the 
soil through the moisture in which they have been dis- 
solved. The moisture of the soil passes through the 
membranous covering of the root fibers, and thence up- 
ward into the i)lant, forming its sap or juice, Sub- 
stances dissolved in this juice ai-e thus able to find their 
way to all parts of the plant. In order to understand the 
rise and flow of sap, and the distriljution of nutritive sub- 
stances, it is necessary to consider three principles of 
natural philosophy called diffusion^ osmose, and capillary 
attraction. 

1. Diffusion. — Diffusion is the term applied to the ten- 
dency of different liquids, and solids dissolved in liquids, 
to become thoi-oughly mixed Avhen placed together. If 
alcohol and water are placed together in the same vessel, 
they quickly mingle, so as to form a uniform mixture. 
If a handful of salt is thrown into a pail of water, it is 
quickly dissolved, and evenly distributed, so that all 
parts are equally salted. 

The same is true if several substances, as salt, sugar, 
and alum, are dissolved in the same water. Each is 
equally distributed as if no other were present. These 
facts are due to the attraction of molecules of alcohol for 
those of water, and the attraction of molecules of water 
for those of salt, sugar, etc. The fact that all the mole- 
cules of water have equal attraction for salt causes the 
salt to be equally distributed between them. If, in any 
way, some of the salt could be withdrawn from a portion 

Wins. Ag. — 6 



66 THE PRINCIPLES OF AGRICULTURE. 

of the water, some of the remaining salt would immedi- 
ately move forward and fill the vacancy, so as to maintain 
an equal distribution. 

The diffusion of water and sulphuric acid may be seen 
by partially filling a glass jar or tube with water colored 
with blue litmus, and pouring through a tube, to the 
bottom, water containing a few drops of sul|)liuric acid. 
The effect of the acid would be to change the blue to 
red. Sulphuric acid is heavier than water, and would 
otherwise remain at the bottom ; but according to the 
law of diffusion, it gradually mingles with the water 
aboi^ until the color of the whole is changed to red. 

2. xQha^. — The term osmose, from a Greek word 
which means to push, is applied to the fact that sub- 
stances which tend to mingle by diffusion will pass 
through a porous partition separating them, and become 
as thoroughly mixed as if no partition were present. If 
a quantity of salt water and a quantity of sweetened 
water are separated by a porous membrane, some salt 
will pass through the membrane one way, and some sugar 
the other way, until both are equally distributed through 
the whole. 

The same is true of other substances dissolved in 
water, and of different liquids separated by a membra- 
nous partition. 

This principle may be illustrated by placing in a ])lad- 
der, or some other membrane, a small quantity of colored 
alcohol, lowering this into a glass of water, and allowing 
it to remain until the water becomes colored, showing 
that some of the alcohol has passed through the mem- 
brane into the water. 

While the membrane, or other substance, must be 
porous, the pores may be very minute. Water, and sub- 



PLANTS. 



67 




The Capillary Curve. 



stances dissolved in it, will find their way through a 

medium whose pores are too small to be seen, even with 

the aid of a microscope. 

3. Capillary Attraction — The attraction of solids and 

liquids for each other, in the case of solids which will nr-i 

dissolve, is shown in the fact that 

the two adhere to each other when 

brought in contact. 

If the edge of a piece of glass is 

dipped into water, the water will 

rise a little distance upon the 

glass, and when it is withdrawn 

some moisture will remain upon 

it. If a small glass tube is placed 

in water, the attraction between 

the two will cause the water to rise in the tube. The 

smaller the tube, the higher the water will rise. 

This principle of attraction between 
solids and liquids, which causes a liquid 
to pass readily through the minute tubes 
or pores of a solid, even upward against 
the force of gravitation, is called capillary 
attraction, from a Latin word, capillus., 
which means a hair. The application is 
to the small, hair-like nature of the tubes 
through which the principle works. A 
familiar example of capillary attraction is 
the rise of oil in the wick of a lamp. The 

attraction of cotton for oil causes the oil to pass rapidly 

upward through the pores of the wick. 

If one end of a towel is placed in a bowl of water, the 

water will gradually pass along the cotton or linen fibers 

until the whole towel is moistened. ^\ 




Direct Capillarity. 



68 THE PRINCIPLES OF AGRICULTURE. 

Application of these Principles to Plant Growth. — These 
three principles all have an application in the passage of 
substances into plants from the soil. Roots are covered 
with a kind of membranous coating. The moisture of 
the soil, passing through this coating, and upward into 
the plant, saturates the plant, or completely hlls it with 
moisture, by the force of capillary attraction. The nutri- 
tive substances dissolved in the moisture likewise pass 
into the plant through its roots. 

By the principle of diffusion, these substances tend 
to distribute themselves equally, not only through the 
moisture of the soil about the roots, but throughout the 
juice or sap of the plant. 

The Absorbing Power of Roots. — The material of which 
the roots of plants are composed has a very strong at- 
traction for water. On this account, the moisture of 
the soil is drawn upward through the roots into the stem 
and leaves with considerable force. This pressure, by 
fdling all parts of the plant, assists in keeping it in a 
firm, upright position. When the supply of moisture is 
cut off by drought, or by severing the root, the plant 
withers and droops. 

It has been found that this force is sufficient to assist in 
the extension of buds and leaves in their growth. It is 
supposed to explain also the tall, slender growth of crops 
in a wet season. The upward pressure of the moisture, 
which is al)undantly supplied to roots in such a season, 
is sufficient to force the different parts of the plant out 
of their normal dimensions. 

TJie Structure of Plants. — The roots, stems, and leaves 
of plants, and in fact all vegetable substances, are origi- 
nally composed of a great number of small cells. These 
generally consist of little membranous vesicles or bags, 



PLANTS. 



69 




Cells from Potato Tuber. 

{Sliowing Starch Grains.) 



which are filled with liquid or solid matter. The cells 
of a potato contain little grains of starch, floating in 
a watery liquid. As the potato ripens, these grains 
become larger. When a ripe potato is boiled, the starch 
grains swell so as to burst 
the cells, and give the pota- 
to a " mealy " appearance. 
Starch is obtained from 
potatoes by grinding to 
break the cells, and then 
washing out the starch. 

Growth consists in the 
multiplication of these 
cells, either by dividing 
the old cell into several 
new ones, or by forming 
several new cells upon the outside of the old one. 

In the lower orders of plants there are some that con- 
sist of single cells, each new cell forming a separate 
plant. Others are composed of a number of these sim- 
ple cells loosely attached to each other. 

The mushroom that grows in a single night, ordinary 
mold, and the blight or smut that sometimes forms 
upon corn and grain, are examples of plants entirely 
composed of these simple, loose cells. 

In the higher orders of plants, ripe fruit and some 
other soft, succulent parts, are also composed of simple 
cells, so loosely connected as to be easily separated from 
one another. 

In the more substantial parts of most plants, however, 
the cells are not so soft and loose, but are firmly con- 
nected together, forming what is called vegctal)le tissue. 

Cells are of diuercnt shapes in the different varieties 



70 



THE PRINCIPLES OF AGRICULTURE. 



of plants, and often also in different parts of the same 
plant. In their simplest forms they are generally spher- 
ical, or globular. In the fiber of wood they are long and 
tapering, firmly joined together by their sides. 




Section of Wood. 

Lengthwise Slice of Wood from an Ailanthm glnndnlosa, or '■'■ Tree of Heaven,''' 

highly magnified. 



Sometimes the covering of the ends of these long cells is 
removed, so that they open into each other, and form a con- 
tinuous tube, through which the sap may flow more freely. 
Fibers of cotton and flax are simply long, single cells. 



PLANTS. 71 

The Flow of the Sap. — The sap is the moisture of the 
soil which has passed upward, through the roots, into 
the plant. The plant is entirely tilled, or saturated, 
with sap. 

By the principle of osmose and the force of capillary 
attraction the sap moves partly along the tubes formed 
by the union of long cells, and partly through the mem- 
branes from cell to cell, until every part of the plant is 
filled. 

When a plant has become saturated, there can be no 
more flow of sap until room has been made for more. 
The flow is kept up, partly by the growth or enlarge- 
ment of the plant, forming new cells which need to be 
filled with moisture, but mostly by the evaporation of 
the moisture or sap from the leaves. 

Leaves contain a great number of minute openings, 
particularly on the under side, which bring the air in 
immediate contact with the sap within. Through these 
openings the moisture of the sap is continually escaping 
into the air by evaporation. 

In damp weather evaporation is slow, and hence the 
upward flow of sap is likewise slow ;. but in dry weather, 
and especially under the influence of the warm sunlight, 
it goes on more rapidly. 

The quantity of water conveyed in this way into the 
atmosphere is very large, amounting during the season 
to many times the weight of the full-grown plant. Soil 
occupied with crops is thus dried much faster than that 
upon which no vegetation is growing. 

The abundant flow of sap from a maple in the spring 
is due to the fact that the tree is not only filled wdth sap, 
but this is placed under some pressure by the force of 
caj)illary attraction. As the tree contains no leaves at 



72 THE PRINCIPLES OF AGRICULTURE. 

this season, there can be no evaporation to reheve the 
pressure. The sugar of the sap is chemically formed in 
the tree, out of the starchy substances stored during the 
previous autumn. 

Nutrition. — Tlie nutritive substances which are de- 
signed to serve as food for plants, and are dissolved in 
the moisture of the soil, include a great variety. 

Each of these is needed in neai'ly all parts of the plant. 
The most of them, however, must undergo chemical 
changes before they are ready to be assimilated, or to 
enter into the structure of the plant. Some of them 
must first rise to the leaves to receive certain changes 
by contact with the atmosphere, and must then pass 
downward again to aJl points where they are required. 

The sap of plants, like the blood of animals, furnishes 
a medium through which the elements of food may find 
%eir way to the points where they are needed, but the 
flow of sap is not at all similar to the circulation of the 
blood. The blood, in its circulation, actually carries sub- 
stances to all parts of the body, and deposits them at the 
points of destination, but there is no such complete sys- 
tem of couAeyance in the sap. It is true that the ele- 
ments of plant food are aided, in passing from the soil 
into the plant, by the upward movement of the sap ; but 
when once in the plant they must act independently of 
this movement, passing sidewise, downward, and in every 
other direction. 

This is to be explained by the principles of diffusion 
mid osmose. 

As salt, when dissolved in water, will extend itself to 
all parts of the water, making its w^ny through interven- 
ing membranes, so these nutritive substances find their 
way to every part of the plant. 



PLANTS. 



73 



The.Power of Selection. — A plant has, in a certain sense, 
the power to make a selection of its food. While any 
substances dissolved in the moisture of the soil will nat- 
urally lind their way ^ 

into the plant, only 
such of these as are 
needed will be taken 
up and made use of. 

Both the sap of tim- 
othy grass, and that of 
clover, for instance, 
contain silica. The 
timothy makes use of 
this to some extent, 
but clover, having lit- 
tle use for silica, per- 
mits it to remain in 
the sap. 

It is believed that, 
in some cases, the 
roots of plants are 
able to produce chem- 
ical changes in some 
elements of soil, and 
even of rocks, with 
which they are brought 
in contact, withdraw- 
ing such parts as are 
required, and leaving the remainder in the soil. 

Flowers and Seeds. — In a general sense, the aim and 
tendency of ])lants is finally to produce flowers, and then 
seeds, which, in their season, are to spring up and pro- 
duce similar plants, so that the variety may continue 
perpetually in existence. 




The Essential Parts of a Flower. 



74 THE rKINCU'LES OF AGRICULTURE. 

The essential parts of a flower are the central, or in- 
terior organs, by which the seeds are formed. These are 
generally surrounded by floral envelopes, called the calyx 
and the corolla^ whose individual leaves, the sepals and 
'petals, give the flower its beauty. 

The central organs are of two kinds, called j^istils and 
stame7is. 

The pistils contain germs from which seeds are formed, 
and the stamens produce a fine dust, generally of a yel- 
low color, called pollen. 

This pollen, falling upon the pistils, fertilizes them, 
and starts the formation of seeds. 

Usually both stamens and pistils grow upon the same 
plant, and near each other in the same flower. In some 
varieties, however, the pistils are borne upon one plant 
and the stamens upon another. This is true of some 
varieties of strawberries, and of hop and hemp plants. 

On account of this peculiarity, it is necessary, in culti- 
vating these crops, to mix plants of both kinds. 

Sometimes the pistils are boi'ne upon one part of a 
plant, and the stamens upon another. An example of 
this is seen in Indian corn. The pollen produced upon 
the tassel falls upon the silk, which is connected with 
the pistils within the ear. 

Pollen dust is produced by some plants in large quan- 
tities, and is carried long distances by the wind. This, 
falling upon different plants of the same species, causes 
a mixture. 

By a transfer of pollen dust in this way, an almost 
endless variety of some species of plants is obtained. 
A green variety of squashes growing beside a yellow 
variety yields a variety partly green and partly yellow. 
Grains of pollen dust, carried by the wind from one corn- 



PLANTS. 75 



field to another, will i^roduce scattering kernels in the 
latter field of the variety contained in the former. 



QUESTIONS. 

"Wliat are plants ? What are the two essential parts of a seed ? 
What is the embryo ? How long will seeds preserve their vitality ? 
Why should new seeds be used for planting? Wliat is the effect 
of planting unripe seeds? What is the effect of selecting the best 
specimens of seeds for planting ? 

What are the three conditions necessary for the growth of seeds ? 
How much moisture is most favorable ? AVhat is the effect of 
planting seeds in soil either too warm or too cold ? What is the 
effect of planting seeds too early in the spring ? Why will seeds 
fail to grow where there is no air ? Under what circumstances is 
it best to plant seeds deeply ? When is it better to cover them but 
lightly ? What causes weeds to spring up after ground has been 
plowed ? Why have these weeds failed to grow before ? 

What are the three processes involved in germination ? Why must 
the seed be filled with moisture ? Why is grain allowed to sprout 
in making malt? Why does sprouting produce heat? 

What are the radicle and the plumule? Why do they start from the 
seed in opposite directions ? Which is more essential to the plant, 
the atmosphere or the soil ? In what points do plants, in their 
f^rowth, resemble animals ? 

Hame the elementary substances that are essential to the growth of 
plants. *; What food do plants obtain largely from the atmosphere ? 
Explain the process by which it is obtained. What has the sun- 
light to do with it ? Why do plants become pale in dark weather ? 
How do plants purify the air ? Do they remove oxygen from the 
air ? Do they purify the air in the night ? Are they beneficial to 
the air in a dwelHng-house ? How are drooping plants revived by 
watering? Do plants obtain nitrogen from the air? 

What are the purposes of roots ? Name some plants which have tap- 
roots ? By what method do roots grow ? How many roots have 
plants? How deep do they sometimes extend? 

Name all the elements of food that plants obtain from the atmos- 
phere. Name those that they obtain from the soil. How do they 



76 THE PRINCIPLES OF AGRICULTURE. 

obtain food from the soil? Explain the principle of diffusion. 
AVhat causes substances to mingle and dissolve so readily ? Ex- 
plain osmose. How are li(iuids, and substances dissolved in them, 
able to pass through a membrane ? To what fact is the term cap- 
illary attraction applied? Why is it so named? Why will a 
whole towel become wet if one end is placed in water ? Why will 
water rise higher in a very small tube than in a larger one ? 

How, according to these principles, do the substances of the soil pass 
into plants ? What effect is produced upon plants by the attrac- 
tion of their roots for water ? Why does a plant droop when the 
soil becomes too dry? 

Of what do the roots, stems, and leaves of plants consist ? In what 
way is growth produced ? Name some plants composed of loose 
cells. What is vegetable tissue ? What is the form of cells in 
different plants? 

Explain how moisture reaches all parts of the plant ? What two 
causes tend to keep up a continuous flow of sap ? How does the 
moisture of sap escape into the atmosphere ? Why does sap flow- 
slowly in damp weather ? Explain the cause of the abundant flow 
of sap from the maple in the spring ? Why does the flow cease as 
soon as the leaves begin to grow ? Does the flow of sap resemble 
the circulation of the blood of animals ? 

In what direction do the nutritive substances move within the plant ? 
AVhat causes them to move ? Can plants choose their food ? 

What is the natural purpose of the growth of plants ? Name the 
different parts of a flower. Explain the purpose of the pistils 
and the stamens. Name some plants that have only one of these 
upon a single plant. Name some that have the two upon differ- 
ent parts of the same plant. How are many different varieties 
of the same species of plants obtained ? Why will not peas and 
beans mix and produce new varieties ? 



CHAPTER V. 

FERTILIZERS. 

Fertile Soil. — The fertility of soil depends upon its 
ability to supply plants with all the elements of food 
which they require. No one of the elementary sub- 
stances which have been enumerated as always found 
in the composition of a plant can be dispensed with. 

As an animal cannot live or thrive without a proper 
supply of the ordinary elements of food, so a i)lant re- 
quires a regular supi)ly of these various elements from 
the soil. A plant poorly supplied with potash or nitro- 
gen, for instance, would produce only a sickly growth, 
and if entirely deprived of these, or of any other essen- 
tial element, would die. 

Fertile soil, therefore, must contain not only large 
quantities of plant food, Init sufficient quantities of every 
kind of food which plants obtain from the soil to supply 
the wants of the crop. 

So, too, soil must not only contain these elements, but 
they must be in a form in which plants can make use of 
them. An acre of soil may contain many tons of nitro- 
gen or phosphoric acid, and yet may be totally unfit 
to produce a crop, because these cannot be converted 
into suitable forms fast enough to supply tlie amount of 
food required. 

The following list gives the percentage of different sub- 
stances which may exist in ordinary dry, fertile soils. 

(77) 



78 THE PRINCn^LES OF AGRICULTURE. 

Per Cent 

Organic matter (containing some nitrogen) . . 9.3 

Phosphoric acid 0.5 

Potassium oxide 0.2 

Sodium oxide 0.4 

Lime 6.0 

Sulphuric acid 0.2 

Carbonic acid 4.2 

Silica . . . c 66.1 

Oxide of Iron , ... 6.5 

Magnesia 0.9 

Alumina 5.5 

Chlorine 0.2 

100.0 

The percentage of many of these seems small, but it 
amounts to a large quantity per acre. One tenth of 
one per cent, of the dry soil of an acre would generally 
amount to two or three tons. 

The quantity of many of these substances required by 
crops is so small that they are practically inexhaustible. 
Of those substances which crops require in larger quanti- 
ties there would be enough to last many years, provided 
they could be changed and made available as fast as 
required. 

The ordinary crop of wheat raised upon an acre might 
require, among other elements, fifteen pounds of phos- 
phoric acid and eighteen pounds of potash. If the en- 
tire amount of these substances naturally contained in 
good soil could be made useful as fast as needed, there 
would be no lack for many years. 

The Effect of Agriculture. — In a state of nature fer- 
tility is naturally maintained. Plants that grow upon 
the soil die and decay upon it. Thus, those elements 
of fertility which have been withdrawn from the soil by 
plants in their growth are returned to it by their death. 



FERTILIZERS. 79 

Tn the process of agriculture, by removing crops we 
take away a quantity of these elements, year by year. 
If this is continued, and nothing is returned to the soil, 
in the course of time it becomes impoverished. The 
supply of plant food is exhausted, and not enough is 
changed to an available form, year by year, to produce 
a crop. 

Land that is " run out " in this way may still contain 
large quantities of some elements of fertility, being de- 
ficient only in a few. By supplying the latter we may 
still keep up the fertility of the land for many years. If, 
for instance, the soil of a certain field contains enough 
available nitrogen to support a crop two years, enough 
phosphoric acid and potash for five years, enough lime 
for ten years, and enough of other substances for a longer 
period, it is evident that after two years we must supply 
nitrogen, after five years phosphoric acid and potash, 
and so on, unless some of these elements have been lost 
in the mean time, or some have been added by natural 
causes. 

The Soil a Storehouse of Plant Food. — Ordinary soil ap- 
pears to be composed of simple, inactive, unchanging 
substances, but in reality it is like a vast chemical labo- 
ratory, in which plant food is continually prepared, and 
either furnished immediately to the plant or kept in store 
for the future. 

A portion of the rocky or mineral parts of soil con- 
tain substances which, when they have been changed by 
chemical action, become food for plants. Among the 
most fertile kinds of soil are those which have been pro- 
duced by the crumbling and decay of granite and lime- 
stone. Vegetable mold, which results from the decay 
of plants and leaves, and which is found to a certain ex- 



80 THE PRINCIPLES OF AGRICULTURE. 

tent in nearly all varieties of soil, is largely composed of 
the elements of plant food, which are gradually rendered 
available, year after year. 

Chemical action, or the formation of plant food in these 
sul)stanccs, is checked by cold weather, but goes on con- 
tinuously in the summer season. It is aided by a proper 
supply of moisture in the soil, by the oxygen and car- 
bonic acid of the atmosphere, and by the small quan- 
tities of ammonia and nitric acid which are brought to 
the soil in rain. 

An application of fertilizers to the soil not only di- 
rectly supplies the elements of plant food, but is also 
useful in furnishing, substances which are needed to 
unite chemically with other substances already con- 
tained in the soil, in order that the latter may become 
serviceable. 

When roots of growing plants arc present, these nutri- 
tive substances are immediately absorbed, so far as they 
are needed. If formed faster than needed, the surplus 
is either retained for future use, or is washed away by 
rains and wasted. Some varieties of soil, particularly 
those containing clay or vegetable mold, are able to 
retain large quantities of these elements for a long time, 
but from loose, gravelly, or sandy soil they are easily 
washed away. 

The Elements Needed in Fertilizers. — A majority of the 
elements of fertility are contained in most soils in 
sufficient quantities to last many years. Those which 
generally fail the soonest, and which we must aim to 
supply in fertilizers, are nitrogen^ phosphor ie acid, and 
potash. 

Some peculiar soils may be wanting in some other 
substance, as sulphur or lime ; but when soils begin to 



FERTILIZERS. 81 

be unproductive, the lack of one or all of the three 
elements mentioned is almost universal. 

Plants require larger quantities of these elements than 
of any other, and hence they fail the soonest. 

Nitrogen. — Nitrogen is an element both essential to 
plants and difficult to obtain. While the air contains 
an abundance of it, but few plants can make use of it 
from that source. It is not generally available to the 
plant in its free state, but in combination with other 
elements. 

There are two compounds of nitrogen in which it is 
believed to be mostly serviceable to plants : they are 
nitric- acid and ammonia. 

1'he plant seems to obtain most of its nitrogen by tak- 
ing up througlx its roots either of these substances, or 
compounds formed by the chemical action of these upon 
other substances. 

1. Nitric Acid (HNO3). — Nitric acid is formed in 
the soil by the decay of organic matter. A small 
quantity of it also exists in the atmosphere, some of 
which arises from the decay of organic substances, and 
some is believed to be produced out of the free nitro- 
gen and oxygen of the air by electric currents passing 
through it. 

This acid, either formed in the soil or washed into it 
from the atmosphere, enters the roots of the plant, either 
directly, or in the form of salts, called nitrates, produced 
by its union with alkaline substances. 

2. Ammonia (NHs).- — Ammonia is also produced by 
the decomposition of animal and vegetable matter, from 
which, unless absorbed and retained by other substances, 
it easily escapes into the atmosphere. It is very soluble 
in water, and is absorbed by various substances, as peat 

Wins. Aon. — 6 



82 THE PRINCIPLES OF AGRICULTURE. 

and decaying vegetable matter, clay, and other soils. 
Charcoal will absorb ninety times its own bulk of am- 
monia gas. 

Ammonia is therefore widely diffused, though in small 
quantities, in the atmosphere, in the land, and in the 
water of the earth. It readily combines with acids, and in 
the atmosphere is not generally found in a free state, but 
combined with carbonic acid, forming carbonate of am- 
monia. This carbonate is dissolved in the moisture of 
the atmosphere, and brought to the earth, where, to- 
gether with the ammonia already contained in the soil, 
it adds to the supply of nitrogenous plant food. 

Only a part of the nitrogen required for producing 
farm crops is furnished in the natural supply of nitric 
acid and ammonia. The farmer adds to this supply by 
furnishing fertilizers which either contain these sub- 
stances or their compounds, or which will produce them 
in the soil hy decay and chemical changes. 

Nitrification. — The vegetable matter which exists in 
ordinary soil in the form of decaying grass, leaves, roots, 
or stable manure, jcontains nitrogen combined with car- 
bon. In this condition it is not available as plant food. 
By a peculiar process called nitrification the nitrogen is 
separated and converted into nitric acid. This acid again 
combines with ])ases in the soil and forms nitrates, as 
nitrate of lime, nitrate of soda, or nitrate of potash, and 
these are easily dissolved and readily absorbed by the 
roots of plants. They are also easily washed away from 
the soil and lost when there are no plant roots ready to 
take them up. 

The process of nitrification is brought about by the 
growth of a minute plant. This plant thrives in warm, 
moist soil, which is sufficiently porous to admit air, and 



FERTILIZERS. 83 

which contains some alkaline substance. During the 
warm summer months nitrates are continuously formed 
in this way to support plants while they are grow- 
ing most vigorously. Young plants sometimes suffer 
from the want of nitrogen in the early spring, before 
the soil becomes sufficiently warm for the formation of 
nitrates. 

Phosphoric Acid (P2O5). — Phosphoric acid, a combina- 
tion of phosphorus and oxygen, is not found free, but 
in combination with potash, soda, lime, etc. 

It is very largely a plant food, and is especially 
necessary for the proper ripening of plants and the 
formation of seeds. Its most common form is that of 
phosphate of lime (CaOPgOs). In this form it consti- 
tutes about one half the substance of the bones of ani- 
mals, which are largely used in preparing this element 
of fertilizers. 

Potash (K2O). — Potash is also an important element 
of fertility, which does not exist in ordinary soil in suf- 
ficient quantity to support a continuous succession of 
crops. 

It is generally obtained and used in the form of salts 
of potash, as carbonate of potash (K2CO3), chloride of 
potash (KCl), etc. Carbonate of potash is the impor- 
tant part of wood ashes. '' New " land is generally well 
supplied with potash in the ashes resulting from the 
burning of trees and brush. 

Artificial Fertilizers. — To supply nitrogen, phosphoric 
acid, and potash to the soil, as well as certain other 
elements which are sometimes needed, substances are 
either manufactured, or are obtained in a natural state 
in different parts of the world. To distinguish these 
from ordinary farm manure, which is the most common 



84 THE PRINCIPLES OF AGRICULTURE. 

and natural fertilizer fur the farmer, they are called 
artificial fertilizers. 

The materials for them are obtained from a variety 
of sources, some of the more common of which are 
as follows : — 

Sources of Nitrogen. — 1. Nitrate of soda, or Chili salt- 
peter, is extensively obtained ni a natural state from 
some parts of South America. 

2. Sulphate of ammonia is obtained for a fertilizer 
from " gas liquor," or the water in which illuminating 
gas has been washed. The ammonia which the liquid 
contains is obtained by treating it with sul})liuric acid, 
with which the ammonia combines. 

3. Fish scrap, meat scrap, dried blood, and all forms 
of animal refuse, are rich in nitrogen, and are generally 
used for manufacturing fertilizers. 

Sources of Phosphoric Acid. — -1. Bones arc largely com= 
posed of phosphate of lime, which is converted into an 
available form, called sujjerphosphate, by an application 
of sulphuric acid. Crushed and ground bones are also 
used directly as fertilizers, but yield their phosphoric 
acid more slowly. Bone-ash, produced by burning bones 
until they crmn])lc easily, is less valuable than ground 
bones, as the process of burning removes from the bones 
what nitrogen they contain. 

2. Bone-black, or charred bone, is used at sugar refin- 
eries for cleansing sugar. After it becomes useless for 
this purpose it is treated with sulphuric acid to convert 
its elements into a soluble form, and is then sold as a 
fertilizer. 

3. Mineral deposits are found at various points of the 
earth containing a large percentage of phosphate of lime. 
Their origin is supposed to have been an accumulation of 



FERTILIZERS. 85 

the bones of animals at some period in the ancient his- 
tory of the earth. Many of these deposits are used as a 
source of phosphoric acid for fertilizers. Those used in 
this country are obtained from South Carolina, in what 
is called " South Carolina rock," and from Canada, in the 
form of a green mineral, called apatite. 

4. By a process of manufacturing steel there is formed 
a waste product, en* slag, which contains phosphoric acid. 
This is sometimes used in preparing fertilizers. 

Sources of Potash. — 1. Wood ashes contain to some 
extent all the mineral or inorganic elements of plant 
food, but are particularly rich in carbonate of potash. 
They have been used as fertilizers since very ancient 
times. Until quite recently they have served as the only 
source of potash for artificial fertilizers. 

2. In the mines of Germany, potash is obtained in 
the form of salts of several varieties. These are known 
as " German potash salts." Chloride of potash, com- 
monly called " muriate " of potash, ol)tained from this 
source, is largely used in this country for fertilizing 
purposes. 

Guano. — Certain islands off the western coast of South 
America have for centuries been the haunt of countless 
numbers of sea birds. The droppings of these birds con- 
stitute guano. It has accumulated in some places to 
the depth of from twenty to fifty feet. The general ab- 
sence of rain in those regions has prevented the valuable 
elements from being washed away. Large quantities of 
this guano are shipped to different parts of the world, 
and are either applied directly to the soil, or used in pre- 
paring other commercial fertilizers. 

Prepared Fertilizers. — The various substances enumer- 
ated may be used singly as fertilizers, or in combination. 



86 THE PRINCIPLES OF AGRICULTURE. 

The most of them need to undergo chemical treatment to 
render their elements available. The work of j3reparing 
and mixing is mostly done at large factories, from which 
the ordinary commercial fertilizers are shipped and sold 
to farmers in all parts of the country. 

The aim in preparing these is to produce a mixture 
containing the three elements, nitrogen, phosphoric acid, 
and potash, in the proportions in which they are needed 
for average soils and crops. 

To meet the wants of particular crops, so far as they 
are understood, special fertilizers are sometimes prepared 
and sold for each crop, containing the three elements in 
varying proportions. 

In addition to the substances mentioned, which furnish 
the three most essential elements of fertilizers, there are 
certain others which serve some purpose, either directly 
or indirectly, in improving the fertility of the soil. 

Lime (CaO). — Lime, or oxide of calcium, is obtained 
in large quantities, in various localities, from " limestone 
quarries." In its natural state it is found combined with 
carbonic acid, for which it has a strong attraction, form- 
ing calcium carbonate (CaCOs). 

Calcium oxide, or quicklime, is obtained by heating the 
calcium carbonate until the carbonic acid is driven off. 

Quicklime has a strong attraction for both carbonic 
acid and water. When exposed to the atmosphere, it 
slowly absorbs both these substances, forming air-slaked 
lime. If brought in contact with water, it unites with it 
so rapidly as to cause great heat, producing calcium 
hydrate (CaO^HO. 

Lime is beneficial to soil in various ways : — 

1. It serves directly as plant food. All plants require 
a small quantity. 



FERTILIZERS. 8T 

2. It combines with, and decomposes, vegetable sub- 
stances, and other elements of the soil, preparing them 
for plant food. 

3. In a general, way, it has a beneficial effect upon 
various kinds of soil, rendering them better adapted for 
agricultural purposes. 

It renders heavy, clayey soil more loose and mellow, 
and sandy soil more compact, so that it will retain more 
moisture. It neutralizes the injurious acids of cold, 
peaty soil, and loosens it for the admission of warm air. 

Many varieties of soil already contain lime in abun- 
dance, but where it is deficient, its application is often 
of great benefit. 

Marl. — Marl is composed of carbonate of lime mixed 
with other substances, as clayey or sandy soil. It some- 
times contains some nitrogen and phosphoric acid. The 
low places where it is found are supposed to be the beds 
of ancient lakes which have dried up. The deposit has 
been formed by the accumulation of shell-fish at the bot- 
tom of these lakes, through long periods of the ancient 
world. Marl is used as a fertilizer in regions near these 
beds, where the expense of transportation is not too 
great. 

Gypsum. — Gypsum, or land plaster, is produced by a 
union of lime and sulphuric acid, giving calcium sulphate 
and water (CaS04 + H^O). 

By heating gypsum, the water is driven off, leaving the 
calcium sulphate, or plaster of Paris. 

It is found in nature, in some localities, and is used as 
a fertilizer where lime and sulphur are needed. It is 
especially beneficial to clover, and other leguminous 
crops. 

Salt (NaCl). — Common salt is composed of sodium 



88 THE PRINCIPLES OF AGRICULTURE. 

and chlorine. As plants contain both these elements, in 
small quantities, salt is of some value as a fertilizer in 
soils where they are lacking. It is also of some benefit 
in preparing plant food by exerting chemical action upon 
other substances. It must be used with caution, as in 
too large quantities it is fatal to vegetation. 

An intelligent and economical use of fertilizers re- 
quires a knowledge of four points : — 

1. What the Fertilizer Contains. — As the composition 
of substances used as fertilizers is determined by chemi- 
cal analysis, this is beyond tlie power of the ordinary 
farmer. The government generally affords protection 
against the sale of Avortliless compounds by requiring 
that the composition of the substance exposed for sale 
shall be printed upon tlie package, and by providing for 
chemical tests of the goods as they are found in the 
market. 

2. What the Soil Requires. — The composition and con- 
dition of soil in different localities, and at different times, 
are so varied, that no general rule for the use of fertil- 
izers can be safely followed. 

One field may require nitrogen, while another may be 
well supplied Avith this, but may lack phos})horic acid, 
or potash, or both. The use of a fertilizer in each field, 
containing an average quantity of each element, might 
be a wasteful practice. 

The only method available to fanners for determining 
what their soil needs is to conduct " field experiments," 
applying different fertilizers to different sections, and 
noting the results. For such a purpose, the three ele- 
ments may be obtained singly in " chemicals." 

Nitrogen, for instance, may be obtained in sulphate of 
ammonia or nitrate of soda; phosphoric acid, in ground 



FERTILIZERS. 89 

bones or dissolved bone-black ; and potash, in muriate of 
potash or sulphate of potash. 

3. What the Crop Needs. — The different crops vary 
considerably in tlie relative quantity of the three ele- 
ments needed. It is important that each be supplied 
with a fertilizer suited to its especial wants. 

By a chemical analysis of different crops, we may learn 
in what proportion the different elements of food are re- 
quired in their formation, and so may obtain some idea of 
the proportion in which these elements should be applied 
to the soil. 

4. The Amount Required per Acre. — Economy in rais- 
ing crops, as in raising animals, requires that they shall 
receive all the food they can consume and pro[)erly as- 
similate. No crop can reach and thus utilize all the food 
present in the soil ; hence, more should l)C furnished 
than enough to cover the wants of a single crop. At the 
same time, a large surplus would involve waste, except 
in soils which are al)le to retain it for future crops. 

Methods of Applying Fertilizers. — The valuable elements 
of most prepai'ed fertilizers are largely soluble in water ; 
and, as the tendency of rain is to wash these parts down- 
ward, they should generally be mixed with the surface 
soil. 

These fertilizers are usually so concentrated as to in- 
jure or destroy seeds and roots when brought into im- 
mediate contact with them. On this account, care should 
be taken, in planting, to place some soil between them 
.nd the sprouting seed. 

It is wiser to place them above, rather than beneath 
the seed, so that the young roots may not be injured, 
and so that their elements may be gradually w^ashed 
upon the roots as needed. 



90 THE PRINCIPLES OF AGRICULTURE. 

As the roots of plants are rapidly extended to con- 
siderable distances in all directions, it is better, where 
much fertilizing material is to be used, to distribute most 
of it evenly through the soil, and apply but little to the 
hill or drill. 

"^Farm Manure. — The chief source of fertility, and that 
ujjon which farmers mainly depend, is stable manure. 
As it is generally impossible to raise good crops without 
supplying some kind of fertilizer to serve as plant food, 
the manure of the farm becomes a matter of the greatest 
importance. The size and nature of the manure heap 
often determine the profits of the farm. It is sometimes 
called the farmer's "- gold mine." 

Success in agriculture depends very largely upon an 
understanding of the nature, the means of preserving, 
and the proper methods of applying farm manure. 

Its Nature. — It differs from the ordinary commercial 
fertilizers in three respects : — 

1. It contains all the elements of food required by 
plants. As farm animals live upon the crops or plants 
of the farm, it is evident that the manure will contain 
the substances which come from these plants, and of 
which they are composed, less so much as the animal 
has assimilated, and converted into flesh, bones, wool, 
milk, etc., and the carbon which has escaped with the 
breath. 

Only a small part of the elements of food are thus 
assimilated and retained by the animal in digestion. 
The amount will depend upon the nature of the animal. 
In the case of young, growing animals, cows giving 
milk, or sheep producing large quantities of wool, the 
proportion retained will be greater than in the case of 
mature animals yielding no increase. It may be stated. 



FERTILIZERS. 91 

as an average, that from eight to nine tenths of the 
manurial elements of the food of animals exists in the 
manure. 

As the elements of manure are the same as the ele- 
ments of plants, it is evident that the manure is suited 
for the growth of other plants, in turn, provided it is all 
preserved and returned to the soil without loss or waste, 
and provided sufficient fertilizing material is added to 
take the place of the part retained by the animal. 

2. It is less concentrated. A ton of average manure 
contains only about 25 pounds of plant food. The re- 
maining 1,975 pounds can be of no direct service as food 
for crops. This renders it more expensive to handle, 
which is sometimes a serious objection where it must be 
conveyed a long distance. 

The bulky nature of manure, however, gives it certain 
advantages. It is of great benefit to heavy soils, by 
making them mellow and porous for the admission of 
air, rendering them drier in a wet season, and at the 
same time enabling them to retain moisture in a time 
of drought. 

The lack of some mechanical " divisor," such as is 
furnished in common manure, is a serious objection to 
continuous farming with artificial fertilizers alone. It 
often becomes necessary to plow in a crop of clover, or 
some other bulky substance, in order to sujjply this want. 
Without some treatment of this kind, soils after a time 
are liable to become solid and compact, and may suffer 
from the slightest drought. 

3. It yields its supplies of plant food more slowly. A 
large proportion of the valuable elements of ordinary 
commercial fertilizers is usually soluble, and immedi- 
ately available to plants. Probably from one half to 



92 THE PRINCIPLES OF AGRICULTURE. 

three fourths of the vakie of these fertihzers may be 
obtained in the first crop after they are applied. 

In stable manure, only a small proportion of these 
elements is soluble and available at first. Not more 
than one fourth of its value is ordinarily obtained the 
first season. The remainder must wait for chemical 
action slowly to reduce it to available forms. 

The Care of Manure. — The value to be derived from 
stable manure depends largely upon the care exercised 
in preserving it. 

Prol)ably nearly one half the yalue of manure through- 
out the country is lost. Some loss is, of course, unavoid- 
able, but it may be largely prevented by proper care. 

There are three general sources of loss : — 

1. Fermeyitation. — Fermentation is a process of de- 
cay, or decomposition, which organic substances un- 
derg-o when broimht in contact with moderatelv warm air. 
Tlie chemical process consists partly of oxidation, pro- 
ducing heat. On this account, it is sometimes called 
heating. 

Some kinds of manure ferment much more readily and 
rapidly than others. 

Sometimes, if tlie process is allowed to continue un- 
checked, it will give to manure the appearance of having 
been partially burned, leaving only a light, unsubstantial 
mass behind. It is then said to 'be " fire-fangcd." 

By fermentation the most valuable elements of manure 
are converted into gases, and tend to escape into the 
atmosphere. Nitrogen is converted into ammonia, and 
carbon into carbonic acid gas. The loss of the former is 
of far greater importance than tliat of the latter, since 
car})on, whicli plants obtain so largely from the atmos- 
phere, is of less value in manure. 



FERTILIZERS. 93 

When the fermentation is going on rapidly, ammonia 
is sometimes formed so fast as to produee a strong, pun- 
gent odor. We may determine Avhether it is eseaping to 
some extent by suspending over the manure heap a piece 
of litmus paper in which the blue color has been changed 
to red by dipping it in some acid. If there is any annno- 
nia escaping, it will gradually restore the color from red 
to blue. 

Slight fermentation would do no harm, and in fact 
may be of some advantage in converting tlie elements of 
manure into available forms, provided there are other 
substances present ready to unite with the gases, and re- 
tain them as soon as they are formed, so as to prevent 
their escape. It is in this way sometimes desirable for 
special purposes, as in compost heaps. Generally, how- 
ever, it is to be avoided, since any advantages gained 
by the process are overbalanced by the loss of esca|)ing 
gases. 

The ordinary methods of checking fermentation are : — 

(1.) By mixing the manure of different animals. 
Some kinds of manure are slow to ferment. When 
these are mixed with other kinds, the fermentation of 
the mass is checked. 

(2.) By keeping the manure heap wet. A certain 
amount of moisture aids fermentation, but an excess 
checks it. It is therefore of some advantage to keep 
the heap as moist as possible without causing loss by 
drainage. 

(3.) By keeping the heap trodden down, so as to 
exclude the air. As the process requires the presence 
of the atmosphere, it is evident that it may be largely 
prevented by excluding the air as much as possible. 

For this reason it is often of great service to allow 



94 THE PRINCIPLES OF AGRICULTURE. 

pigs, or other animals, to run upon the manure heap, 
so as to keep it in a compact condition. 

2. The Eacape of Liquids. — The Hquid parts of manure 
contain more than one half their value. It is important 
that some dry, spongy substance, as straw, leaves, dried 
muck, or dry soil, be used to absorb and retain them. 
The niti'ogen which serves to form ammonia by fermen- 
tation, is largely contained in the liquids, and the pres- 
ence of these substances in some measure prevents the 
escape of ammonia, by combining with it or aljsorbing it. 

The same purpose may be more fully accomplished by 
applying to the liquids sulphuric acid, or gypsum, which 
is partly composed of that acid. 

3. Exposure to Rain. — The liquid parts contained in 
manure, and held by absorbents, are readily washed out 
by heavy rains. Both ammonia and nitric acid, the two 
available forms of nitrogen, are largely lost in this way, 
as well as some other elements. 

When manure is piled in heaps upon land which is to 
be cultivated, it is true that these elements are washed 
into the soil. This, however, involves waste, as the 
small plots beneath the heaps are too much overstocked 
with these valuable substances to be able to render any 
adequate returns in the crops. 

To prevent waste by washing, manure should be kept 
under cover ; or, if exposed, should be so protected as 
to receive only a small amount of rain, which would do 
no harm. 

Methods of Applying Manure. — Whatever particular 
methods are employed in applying manure to the soil, 
there are two general principles that should always be 
borne in mind : — 

1. It should be applied as soon as possible. All 



FERTILIZERS. 95 

waste, either by fermenting or washing from the heap, 
is avoided as soon as the manure is scattered upon or 
incorporated with the soil. By piling it in heaps, and 
allowing it to ferment, it may be rendered more suitable 
for the immediate wants of certain crops, but this is at 
the expense of some of its value. When applied without 
such fermentation, it may be slow to yield its elements the 
first season, but these are preserved for future years. 

2. It should be rendered as fine as possible, and thor- 
oughly mixed with the soil. Those parts which are sol- 
uble at first may be washed out, and distributed evenly 
enough for practical purposes, under any methods ; but 
in order to secure the benefit of the mechanical effect 
of mixing the solid parts with the soil, and the chemical 
effect produced by these upon the soil in decomposition, 
it should in some way be finely divided, and thoroughly 
mixed with the soil, so as to bring its particles into con- 
tact with as many particles of the soil as possible. 

Swamp Muck. — Muck or peat beds are numerous in 
low, wet places, throughout a large portion of the country. 
Muck consists of partially decayed vegetable matter, which 
has accumulated through past ages. It is of considerable 
value as a fertilizer. It is especially rich in nitrogen, 
samples often yielding from one to three per cent, of it. 

The fertilizing elements of muck, however, are in the 
form of certain acids, or insoluble compounds, which are 
not, in their natural state, available to plants. Before it 
can be of much service it must be treated with some alka- 
line substance, so that its acids may be neutralized and 
its elements converted into available forms. 

This may be accomplished in three ways : — 

1. By long continued exposure to the air. If taken 
from its bed and exposed to the air, it will be gradually 



96 THE PRINCIPLES OF AGRICULTURE. 

but Ycrj slowly changed by contact with ammonia and 
other substances which exist in small quantities in the 
atmosphere. This course is not very practicable, as sev- 
eral years are required to effect a complete change. 

2. By mixing it with some alkaline substance, as lime^ 
wood ashes, or some of the salts of potash. If united in 
a compost with a small quantity of these substances, the 
desired change is soon obtained. 

3. By mixing it with stable manure. This is a very 
profitable method of treating it. A twofold purpose is 
accomplished : the manure furnishes the alkaline ele- 
ments for the muck, and the muck retains those elements 
of the manure which would otherwise escape into the air 
by fermentation. For this purpose, one part of manure 
is regarded as sufficient for three parts of muck. 

Muck as an Absorbent. — Muck, like ordinary vegetable 
mold, possesses the property of absorbing large quanti- 
ties of water. As taken from the swamp, two thirds or 
three fourths of its weight is water. In drying, its bulk 
is greatly reduced. This property renders dried muck 
an excellent absorbent for the liquids of the stable. 
These liquids are exactly suited to produce the proper 
changes in the muck. 

Muck may be profitably applied to land not w^ell sup- 
plied with humus, or vegetable mold. 

The Value of Muck. — The elements of which ordinary 
muck is composed give it a nominal value about equal to 
that of stable manure. Its real value is reduced, ot 
course, by the labor and exi^ense of procuring, compost- 
ing, etc. 

There is a wide difference in the quality of muck from 
different localities, depending upon the nature of the sub- 
stances out of which it has been formed. 



FERTILIZERS. 97 

In some cases it contains a large quantity of ordinaiy 
soil, or other comparatively worthless matter. Some 
samples yield three or four times as much nitrogen as 
others. Before much expense is incurred in procuring 
muck from any particular bed, some idea of its value 
should be obtained, either by chemical analysis or some 
other experiment. 

Some idea may be obtained of the proportional amount 
of worthless sand, or other mineral matter which the 
muck contains, by placing a small quantity in a tube or 
glass of water, shaking the glass thoroughly, and, after 
allowing it to stand for some time, noting the quantity of 
mineral substances which settle to the bottom. 

QUESTIONS. 

What is fertile soil ? Name the elements necessary to make soil fer- 
tile ? Would a soil containing no sulphur be fertile? Would scraps 
of leather, which are largely composed of nitrogen, add to the pres- 
ent fertility of soil ? In what way is the fertility of the soil naturally 
maintained? What is the effect of raising crops ? 

What processes are going on in the soil ? Do rocks furnish food for 
plants ? AVhat effect has cold weather upon the chemical processes 
in the soil ? What is the effect of the atmosphere ? How do fer- 
tilizers aid the chemical action ? AVhat becemes of the fertilizing 
substances formed in the soil? Why is it more important that 
loose soil should be alwajs occupied with vegetation than clayey 
or mucky soil? 

What elements are most generally lacking as soil becomes impover- 
ished? Why is nitrogen expensive as a fertilizer? In what forms 
does it generally become food for plants ? Where is nitric acid 
found, and how is it produced ? How is ammonia formed ? Where 
is it to be found in nature ? In what way does the farmer add to 

. the natural supply of nitric acid and ammonia ? 

Wliat is meant by nitrification ? How is the process brought about ? 
What conditions are necessary ? Why is the supply of nitrogen 
smaller in the early spring than in summer ? 
Wins. Agk. — 7 




98 THE PRINCIPLES OF AGRICULTURE. 

Of what is phosphoric acid composed V In what forms is it 
found ? Of what special use is it to plants ? Why is ne\ 
generally well supplied with potash? 

What do artificial fertilizers usually contain ? From what sourtes 
nitrogen obtained for these fertilizers ? Name the different soif'ce^ 
of phosphoric acid. How is potash obtained V 

What is guano ? What other substances are sometimes useful as fer- 
tilizers besides those mentioned ? In what form is lime found ? 
How is quicklime produced ? What is air-slaked lime ? In what 
three ways does lime benefit soil ? 

What is marl? Give the history of its formation. Of what use is it 
as a fertilizer ? 

What is gypsum? How does it benefit soil? Is salt a fertilizer, 
and how ? 

What points should be understood in order to make a proper use 
of fertilizers ? How may farmers learn what fertilizers contain ? 
How can they learn what the soil requires ? Why does one crop 
need a different fertilizer from another ? Why must soil contain 
more fertilizing material than the crop uses ? Would the surplus 
be wasted in a clayey soil ? 

Why should chemical fertiHzers be placed near the surface of the 
soil? Why should they not be allowed to come in contact with 
seeds and roots ? Why should but little be used in the hill ? 

Why is the manure heap sometimes called the farmer's gold mine? 
In what three respects does stable manure differ from commercial 
fertilizers? Why is it a complete fertilizer? 

What part of the elements of plants is retained in digestion? Of 
what advantage is the bulky nature of manure ? How does it ren- 
der land more moist in a dry time ? What part of the value of 
manure may be obtained in the first crop? What are the three 
sources of loss to which stable manure is subject? 

AVhat is fermentation ? How is the heat produced? AVhat substan- 
ces are lost by fermentation ? AVhy is fermentation desirable in a 
compost heap? In what ways may it be partly prevented ? 

What is the chief advantage of allowing pigs to run upon the manure 
heap ? What is the value of the liquid parts of manure ? What 
element gives them their chief value ? What are the benefits of 
using absorbents in the stable ? 

Of what special benefit is gypsum in manure ? How can there be any 



FERTILIZERS. 99 

waste from manure heaps piled upon cultivated land ? Can there 
be any loss to manure while it is frozen ? What two general points 
should be observed in the use of manure ? Why should it be ap- 
plied to the land as soon as possible ? What are the advantages of 
rendering it fine ? 
In what does the chief value of swamp muck consist ? Why is it of 
little value when first obtained ? In what three ways may the neces- 
sary changes in its nature be brought about ? Why are alkaline 
substances needed ? Why is the practice of mixing it with stable 
manure especially profitable? Why is it a good absorbent ? Give 
some idea of the value of muck. 



CHAPTER VL 

CULTIVATION. 

Cultivation, or the mechanical handling of soil for the 
benefit of crops, includes a large part of the labor of 
farming. 

An understanding of the reasons for the different pro- 
cesses embraced in the tillage of the soil, and of the 
benefits to be derived from them, is essential to success 
in agriculture. 

Purposes. — The purposes of cultivation may be classi- 
fied as follows : — 

1. To break up the soil, or make it " mellow^'' so that 
the roots of plants may easily penetrate it. 

The roots of a few varieties of plants are very hard 
and firm. 

Some are provided with a sharp point at the tip, so 
that they arc al)lc to penetrate hard sul)stances. Quitch- 
grass roots will sometimes grow entirely through a 
potato. But the roots of most agricultural plants are 
more delicate, and make their way with difficulty through 
hard soil. 

In poorly cultivated soil, filled with hard lumps, roots 
are found to occupy the mellow portions, avoiding the 
lumps. To leave the soil in a lumpy condition is there- 
fore to reduce the extent of the feeding ground of the 

plant. 

(100) 



CULTIVATION. 101 

The depth to which roots penetrate is largely de- 
termined by the depth to which the soil is stirred in 
cultivation. 

2. To admit air to the roots. 

Most agricultural plants of temperate climates will 
live and thrive only in soil which is sufficiently porous to 
admit air. 

Experiments show that the roots of such plants, as 
well as the foliage, reqmre the presence of free oxygen. 
The plants either die, or produce a feeble, sickly growth, in 
compact soil, or in soil continuously saturated with water. 

There are exceptions, as in case of the cranberry plant 
and rice, which thrive best in soil completely covered 
with water during a portion of the ycfar. 

3. To hasten the decomposition of the soil, and the 
formation of plant food. 

The chemical processes in the soil are hastened by 
exposure to the air. They are partly dependent upon a 
supply of oxygen, carbonic acid, etc., from the atmos- 
phere. By loosening the soil, so as to admit air, and by 
exposing different portions of it to the surface in culti- 
vation, we increase its fertility by hastening the forma- 
tion of plant food. 

The practice of " summer fallowing," which is some- 
times followed, consists in preparing ground for a future 
crop by plowing and harrowing repeatedly, so as to ex- 
pose it as much as possible to the beneficial influences of 
the atmosphere. 

4. To mix fertilizers with the soil. 

Plants thrive best, not where their roots find pure fer- 
tilizer in some spots, and poor soil in others, l)ut where 
the two are so completely mixed as to render the whole 
a uniform medium of rich soil. 



102 THE PRINCIPLES OF AGRICULTURE. 

The benefit to be derived from both fertilizer and soil 
depends partly upon their combination with each other. 

5. To kill weeds. 

Weeds are injurious to growing crops in various ways : 

(1.) By occupying the soil to the exclusion of culti- 
vated crops, and forming a shade, depriving them of the 
beneficial influences of sunlight. 

(2.) By withdrawing moisture from the soil, which 
is taken up as sap and transferred to the atmosphere 
through the leaves. The amount of water thus removed 
from the soil, where weeds are numerous, may cause a 
crop to suffer from want of moisture, while a crop upon a 
neighboring plot free from weeds will be amply supplied. 

(3.) By withdrawing food from the soil upon which 
crops would otherwise feed. 

The quantity of available plant food in the soil at any 
time is limited. The strongest, most vigorous, and quick- 
est growing plants are sure to obtain the greatest share. 
Most agricultural plants are not so vigorous when young 
as the ordinary weeds. Weeds grow much faster at first, 
and so tend to starve out other crops. 

Weeds should always be destroyed when young and 
small. If allowed to grow until they attain considerable 
size, they damage the crop, and are more difficult to ex- 
terminate. They are plants, some varieties of which 
might be of service in their proper places, but they can- 
not be made useful w^hen growing in the midst of other 
crops. 

Although returned to the soil, they reduce the avail- 
able fertility of the farm l)y taking up the elements of 
plant food and converting them into vegetable tissue, 
some of which may require years to be again trans- 
formed into soluble matter. 



CULTIVATION. 103 

6. To regulate the supply of moisture. 

A proper degree of moisture is an essential condition 
for the growth of crops. Either too much or too little 
is injurious. 

During the hot summer months, however, when crops 
are growing fastest, they generally suffer more from a 
lack of moisture than from an oversupply. In the case 
of " hoed " crops, the amount of moisture in the soil may 
be increased by proper cultivation. 

In dry weather moisture finds its way to the surface 
by capillary attraction, and evaporates rapidly. A 
*' mulch," or light covering of straw, or leaves, or any 
other substance, keeps the ground moist by retarding 
this evaporation. By stirring the surface soil and keep- 
ing it light and porous, a similar effect is produced, the 
loose soil serving as a mulch. 

Since the pores in this soil are too large for capillary 
action, the moisture fails to reach the surface. 

7. To afford particular treatment to special crops. 
There are some crops that require special treatment, 

or handling of the soil about them, to insure the most 
successful growth. 

,, Some plants, for instance, are supposed to thrive better 
when the soil is built up into '' hills ■ ' about them. The 
root crops require a soil made mellow to a great dc})th. 

Plowing. — The plow has been regarded, through all 
ages of the world, as tlie characteristic implement of the 
farmer. The first plow ever used w^as nothing more than 
a stick of wood, with which the ground was stirred or 
scratched. The history of the plow and its improve- 
ments corresponds closely to the history of civilization 
and improvements in the art of agriculture. It is still 
nn indispensable implement of tillage. Thoroughness of 



104 THE PRINCIPLES OF AGRICULTURE. 

cultivation and success in farming depend largely upon 
the plow and the use made of it. 

Deep Plowing. — As a general rule, ground is not 
plowed to a sufficient depth. The soil below that part 
which is stirred in cultivation is generally of little direct 
service to crops. 

The subsoil is often too hard to allow roots to pen- 
etrate it freely. As it is buried away from the atmos- 
phere, the chemical changes which would convert its 
materials into plant food are very slow. 
• By bringing it to the surface, and mixing it with the 
fertilizers and fertile soil, these materials are made more 
rapidly availal)le. 

Economy in farming requires that large crops shall be 
produced upon small areas. By deepening the cultivated 
soil, and thus enlarging the extent of space and increas- 
ing the supplies of food availal)le to the roots of plants, 
we attain this end. 

Deep tillage, also, has much to do with regulating the 
supply of moisture. In wet seasons it affords drainage 
by providing more space for the surface water to pass 
into the porous soil beneath. 

In a time of drought, as the roots of crops have been 
able to extend themselves more deeply into the soil, they 
are able to obtain a supply of moisture, and arc not so 
much injured by the drying of the surface. 

While deep plowing has these advantages, there are 
some cautions to be observed. To plow land at first 
much deeper than ever before, would bring to the surface 
a large quantity of crude soil. Unless a great amount 
of fertilizer is applied, this poor soil is liable to injure 
and retard the growth of young plants before their roots 
can penetrate to the better soil below. This difficulty 



CULTIVATION. 105 

may be avoided by making the deepening of the soil a 
gradual process, plowing each time a little deeper than 
before. 

Some sandy or -^alluvial soils are naturally so loose as 
to admit air and roots freely. Such soil, on the one 
hand, is not so much in need of deep plowing ; and, on 
the other hand, if the lower portions are brought to the 
surface, they can do no harm, since they have become 
adapted for plants by the presence of air and the fertil- 
izers which have been washed downward. 

It may not always be wise to plow deeply. In the 
varied processes of cultivation, there may be occasions 
when shallow plowing will, for the time being, better 
accomplish the particular end desired ; as, for example, 
when the lower soil is already sufficiently loose, and we 
simply wish to destroy weeds or n\ix fertilizers with the 
surface soil. 

Subsoil Plowing. — The subsoil plow follows in the bot- 
tom of the furrow made by tlie ordinary plow, stirring 
the lower soil and allowing it to remain in the same 
position. By its use some of the advantages of deep 
tillage are gained without the necessity of bringing the 
poor subsoil to the surface. 

The Time to Plow. — It is an important question at 
what time plowing should be done ; whether as long as 
possible before the seed is planted or just before, — in 
the fall or in the spring. 

There are two sides to the question. After land is 
plowed, and exposed loosely to the atmosphere, chemical 
changes go on more rapidly, converting the elements of 
fertility into a soluble form. On the other hand, the soil 
is more exposed to the washing of i-ain. 

As all vegetation has been destroyed by plowing, de- 



106 THE PRINCIPLES OF AGRICULTURE. 

priviiig the soil of the presence of living roots, which 
would absorb and hold these elements, they are liable to 
be lost as fast as formed, unless the soil from its nature 
is able to retain them. 

In general, the answer to the question will depend 
upon the nature of the soil, the climate, and the particu- 
lar crop to be raised. 

A clayey or mucky soil would be free from the objec- 
tion mentioned, while in the case of a sandy or gravelly 
soil the loss by washing might be greater than the gain 
by exposure to the atmosphere. 

In cold climates, where the ground remains frozen 
through the winter, there can be no loss during this 
season, and plowing in the fall gives land the benefit of 
the crumbling and disintegrating effect of frost. 

In climates where the ground does not freeze, and 
where rain is abundant during winter, there is a liability 
of large loss both by washing out the soluble elements, 
and by washing away the finest and richest parts of 
the soil. 

For raising particular crops there may be special rea- 
sons for plowing in the fall or in the spring, according 
to the special wants of the crop. While ground plowed 
in the fall has received certain changes from exposure to 
the air and the action of frost, that plowed in the spring 
will naturally be more loose and porous. 

Harrowing. — Next to the plow, the harrow is the most 
important implement of agriculture. The purpose of 
harrowing is chiefly to pulverize and level the soil, and 
a thorough performance of this work affords all the gen- 
eral advantages of tillage. It prepares the soil for roots, 
admits air, favors the formation of plant food, and 
thoroughly mixes fertilizers with the soil. Experiments 



CULTIVATION. 107 

hav^j a^iown that land well harrowed will yield better 
crops than land poorly harrowed, but supplied with a 
greater quantity of fertilizers. 

^oUiiig. — Rolling is a useful process in tillage under 
certain circumstances. It crushes and pulverizes lumps 
of soil which have escaped the work of the harrow. 
When the soil is very dry and loose, rolling presses it 
more compactly about seeds, bringing them moisture by 
capillary action, and hastening their germination and 
growth. It serves a good purpose in the spring, by 
pressing into the soil the roots of grass which have been 
thrown out by the action of frost. Clayey land, when 
wet, is injured by rolling, as the particles of soil are 
pressed too closely together to admit air, and in drying 
form a hard crust upon the surface. 

Cultivating. — The frequent cultivating or stirring of 
the surface soil between the rows of hoed crops, during 
the period of their active growth, is beneficial, both by 
killing weeds as soon as they appear, and preventing 
the loss of moisture. In every shower and rain-storm 
the particles of soil are washed and beaten together so 
compactly as to cause moisture to rise to the surface 
by capillary action and evaporate. By loosening the 
surface soil repeatedly, this is prevented. 

As the rootlets of plants ompletely fill the soil, ap- 
proaching very near to the surface, this cultivation should 
generally be shallow. While the surface soil which is 
stirred in cultivation retains the moisture beneath, it 
becomes drier itself because of its loose condition. 

By cultivating deeply among crops, we may prevent 
roots from occupying the upper portions of the soil, not 
only by repeatedly breaking them, but by rendering this 
part of the soil too dry. 



108 THE PRINCn^LES OF AGRICULTURE. 

Draining. — The draining of land, for the purpose of re- 
moving surplus water in wet seasons or in wet places, is 
accomplished either by surface drains or by underd rains. 

Surface di'ains, or ditches, are of some advantage in 
removing the surplus accumulation of water from the 
surface of the ground. Besides being unsightly and in- 
convenient, they have the disadvantage of causing some of 
the richer portions of the surface soil to be washed away. 

Underdrains are buried out of sight, involve no waste, 
and accomplish the purpose more effectually. The gen- 
eral advantages to be gained by underdraining wet land 
are as follows : — 

1. It renders the lower soil available to roots. 

As the roots of most agricultural plants cannot live 
without the presence of oxygen, they cannot occupy 
soil which is completely saturated with water. Where 
the lower portions of soil are filled with water, roots 
are necessarily confined to the surface soil. By drain- 
ing, we afford them an opportunity to make their way 
downward. 

2. It admits air to the lower soil. 

From soil whose pores are filled with water, air is, of 
course, excluded. In such soil the formation of plant 
food mostly ceases. In a muck bog the humus retains 
its elements in an insoluble condition for centuries. 

?)Y draining the water out of soil, we admit air, and 
provide for the formation of plant food. 

3. It secures the benefits of rain. 

Rain water, containing nitric acid, ammonia, etc., is a 
source of fertility. In falling upon soil that is already 
filled with water, it cannot penetrate into the soil, but 
runs away upon the surface. Thus, the benefits of the 
rain are lost. Where water is withdrawn from the soil 



CULTIVATION. 



109 



by drains underneath, falling rain, instead of flowing 
^way, filters through the soil, and, except iii case of loose 
Sand or gravel, leaves its fertilizing elements behind. 

4. It prevents the injurious effects of a drought. 

In a time of drought, while the surface soil becomes 
very dry, there is generally sufficient moisture below. If 
the lower portions have 
been previously satu- 
rated so as to prevent 
roots from occupying 
them, the plant is now 
unable to obtain a sup- 
ply of moisture, as its 
roots are surrounded 
with the dry surface 
soil ; but if the surplus 
water has been drained 
away, so that the roots 
have been able to make 
their way downward, 
when a drought occurs 
the plant may obtain 
its moisture through 
these lower roots. 

5. It renders ivet land available for tillage. 

It is often the case that the wet lands upon the farm 
are the richest in plant food. Many low, wet places con- 
tain an accumulation of vegetable mold, and other fer- 
tile matter washed in from the land around them. By 
draining the water out of these places, we render them 
permanent sources of wealth. 

Some farms are split up into small, irregular plots, by 
narrow tracts of land, too wet for tillage. By draining 




Effect of Underdrainage. 

I, Drnin-pipe. B, Point below ivhich the soil is 
usjtalli/ saturated. C, Point to which the water 
settles in a dry time. 



110 THE PRINCIPLES OF AGRICULTURE. 

these tracts, one continuous field may be formed out of 
a number of plots, which is of great advantage in the 
business of farming. 

6. It increases the warmth of the soil. 

The evaporation of water is a cooling process. It ab- 
sorbs heat from the substance from which the moisture 
escapes. An object may be cooled in hot weather by 
covering it with a damp cloth. Damp clothing gives the 
body a chill, not so much on account of the presence of 
the moisture in the clothing, as from its evaporation in 
drying. So wet land is always cool, because, on account 
of the presence of water, evaporation is always going on. 

The warmth of soil is promoted by drainage, not only 
by drawing the Avater away from beneath, and preventing 
evaporation, but also by admitting warm air. 

Rotation of Crops. — A knowledge of the fertility and 
cultivation of the soil is not complete without an under- 
standing of the principles involved in the rotation of 
crops, or an arrangement of different crops to occupy the 
same land successively. 

It is a familiar fact, that, when the same kind of crop is 
raised upon land year after year, the yield becomes less 
and less ; and that, where one crop fails to yield good re- 
turns, another may flourish. This fact leads to the prac- 
tice of changing frequently from one crop to another. 

The advantages of this practice are as follows : — 

1. It mahes use of all the elements of plant food. 

Different crops require the elements in different pro- 
portions. It is not often that these elements are sup- 
plied by the soil in the exact proportion required hy any 
particular crop. 

Potatoes, for example, require more potash than wheat, 
and wheat requires more phosphoric acid than potatoes- 



CULTIVATION. Ill 

If potatoes should be raised upon the same land con- 
tinuously, tlie supply of available potash would soon be 
exhausted, while there might still remain in the soil an 
excess of phosphoric acid. 

In order to continue to raise potatoes upon this land, 
it would be necessary to undergo the expense of adding 
a supply of potash. At the same time, the surplus of 
phosphoric acid, for which the potatoes have no use, 
might be washed out of the soil and wasted. If some 
crop, like wheat, requiring more phosphoric acid should be 
substituted for potatoes, a good crop might be obtained, 
and in the mean time the decomposition going on in the 
soil would render a new sup])ly of })otash available. 

2. It keeps the land occupied. 

Many of \hQ cultivated crops have a short season of 
growth. After they are harvested, the land remains un- 
occupied until the following season. 

During this time the formation of plant food in the 
soil is continued, and is liable to be lost, as there are 
no growing crops present to make use of it. 

By following the crop immediately with some other, 
as winter grain, or grass, such loss may be avoided. 

3. It prevents the loss of substances which have been 
washed doum into the subsoil. 

The roots of some plants naturally grow near the sur- 
face of the soil. In such cases, some of the elements of 
food may be washed down below the reach of these roots. 
By following with a crop whose roots tend to penetrate 
farther downward, these may be gathered up and saved. 

Clover, which has a deep tap-root, will generally grow- 
well after crops having branching roots, like wheat or 
barley ; and, on the other hand, these will thrive well 
after clover. 



112 



THE PRINCIPLES OF AGRICULTURE. 



4. It secures the varied advantages of cultivating the 
soil. 

When land is continually occupied with one crop, like 
grass, it may become too hard and compact, and the for- 
mation of plant food may be checked. By stirring such 
soil, and exposing it to the atmosphere in cultivation, we 
hasten the chemical changes, and unlock the supply of 
food which nature has in store. 

There are many old meadows and pastures, regarded as 
worn out and worthless, which, if subjected to thorough 
cultivation, might yield profitaljle returns. 

5. It pr(?ye/i^s the increase of weeds and injurious 
iiisects. 

In cultivating certain crops, we may supply conditions 
favorable to the growth of certain varieties of weeds. If 
the crop is continued in the same soil, these weeds will 
naturally increase. Proper management requires a 
change to some other crop with which such weeds will 
not thrive. 

It is well known that injurious insects, like the potato 
beetle, will tend to increase on land which is repeatedly 
occupied by the particular crop upon which they are 
accustomed to prey. 

The following arc examples of rotations which arc 
sometimes adopted : — 



Indian corn . . One year. 

Potatoes . . . One year. 

Wheat . . . . One year. 

Clover .... Two years. 



Clover . 
Tobacco 
Wheat . 



Two years. 
One year. 
One year. 



Wheat 
Potatoes 
Barley 
Clover . 



Cotton . . 
AVheat . . 
Clover or peas 



One year. 
One year. 
One year. 
One year. 

One year. 
One year. 
One year- 



CULTIVATION. 118 



QUESTIONS. 

What are the different purposes of cultivating the soil? What is 
the effect of leaving land in a lumpy condition ? Name all the 
reasons you can think of why plants will not thrive in hard soil. 
AVhy do plants obtain more food in a loose soil ? What reasons 
can you give for mixing fertilizers thoroughly with the soil? 

In what three ways do weeds injure crops? How do they dry the 
ground ? Why should they be destroyed when small ? Since they 
are not removed from the soil, how do they reduce its fertility ? 

In what way does cultivation increase the supply of moisture ? Give 
several arguments in favor of deep plowing. Give several reasons 
why roots do not generally occupy, to any great extent, the soil 
below that which is stirred in plowing. 

What influence has deep tillage upon the supply of moisture? What 
has it to do with economy in farming? Why is it unwise to plow 
very deeply at first? What kinds of soil may not need deep plow- 
ing? What are the advantages of subsoil plowing? 

Name the arguments in favor of plowing in the fall. Give those 
in favor of plowing in the spring. What are the general con- 
clusions in the matter? AVhat are the advantages of thorough 
harrowing ? 

Name all the reasons you can think of why crops grow better in 
soil thoroughly pulverized. What arc the advantages of rollino- 
ground? Under what circumstances is it injurious? What are 
the different benefits of cultivating hoed crops ? AVhy should the 
ground be stirred after every rain-storm? Why should this cul- 
tivation generally be shallow ? 

How may surplus wat^.- be carried away from a field ? What are 
the disadvantages of surface drains ? Name the different advan- 
tages of underdrains ? Why do roots grow deeper where drains 
are provided ? In what two ways do they render land more fer- 
tile ? How do they prevent land from suffering from a drought ? 
How do they render soil warmer ? 

What is meant by a rotation of crops ? What are the advantages of 
a rotation ? Give examples of rotations sometimes adopted. 
Wins. Agr. — 8 



CHAPTER YII. 

ANIMALS. 

THE two forms of life ujion the earth are plants and 
animals. The chief purpose of vegetable life is to 
supply the wants of animal life. The principal object in 
raising plants, or crops, in agriculture, is to obtain a 
supply of food for animals. 

A knowledge of these crops is not completed until we 
have considered them as fed to animals to produce meat, 
milk, wool, work, etc. 

It is very important to understand the nature, the 
peculiarities, the best methods of feeding, and the proper 
care and management of our domestic animals. 

The Composition of the Bodies of Animals. — The bodies 
of animals are composed of very nearly the same ele- 
ments as plants. 

Some animals, like the cow or horse, live mostly upon 
vegetation, and are called herhivorous^ or plant-eating 
animals. Others, like the cat and dog, live largely upon 
the flesh of other animals, and are called caryiivorous^ 
or flesh-eating animals. Some live partly upon plants 
and partly upon animals and animal products. 

But animal products, as meat, milk, eggs, etc., are 
produced from vegetable matter, so that plants are the 
original source of all animal food. 

The only substances that enter into the bodies of ani- 
mals, apart from plants, and animal products produced 
(114) 



ANIMALS. il5 

from plants, are water, oxygen from the air, and small 
quantities of mineral matter, such as salt, lime, pot- 
ash, etc., with which animals must be supplied when 
these are not furnished in sufficient quantity in the regu- 
lar food. 

The process of animal life consists in converting the 
substances of plants into the substances of the animal 
body, or in making them serve the different wants of the 
animal. 

The substances forming the animal body may be divided 
into four classes : — 

1. Water. — Water is generally the largest ingredient, 
comprising from one third to two thirds of the entire 
weight. It is essential to plants, furnishing a medium 
through which the elements of food may be distributed. 
In animals, it hlls a similar office. It forms four fifths 
of the blood, and exists in the juices throughout all parts 
of the body. 

2. Nitrogenous Substances. — Nitrogenous substances, 
or substances containing nitrogen, are of first impor- 
tance in the animal body. They make up the muscular 
tissue, or lean meat, the nerves, the skin, hair, wool, 
feathers, horns, etc. They also form a large part of the 
solid matter in the blood. 

3. Fat. — Fat does not fill so important an office as 
the nitrogenous substances. It does not make up the 
tissues and other essential parts of the body. It is al- 
ways present, however, in greater or less quantity. Par- 
ticles of -fat are to be found scattered between the fibers 
of the muscles. In well-fed animals fat is also stored up 
in large quantities beneath the skin, and about the bones 
and internal organs. 

There are several varieties of animal fats, as stearin, 



116 THE PRINCIPLES OF AGRICULTURE. 

palmitin, and olciii. Some of them, like stearin, are 
hard, and some, like olein, are either fluids or are easily 
melted. 

4. Ash. — The mineral parts of the animal are gener- 
ally called the ash, because they are incombustible, or re- 
main as ashes after burning. They are chiefly found in 
the bones, where they are needed to give firmness and 
hardness. They are comjjosed chiefly of phosphate of 
lime, carbonate of lime, phosphate of magnesium, and 
phosphate of potassium. 

The following table will give an idea of the average 
percentage composition of the bodies of domestic ani- 
mals, after deducting the contents of the stomach and 
intestines : — 

Compositum of Bodies of Animals. 

Per cent. 

Water 51.9 

Nitrogenous matter 14.4 

Fat 30.3 

Ash 3.4 

100.0 

The Purposes of Food. — The different purposes which 
food must serve in the animal system are : — 

1. To increase the Size of the Body. — Mature ani- 
mals, whose size and weight remain constant, require no 
food for this purpose ; but in young, growing animals, 
and those passing from a lean to a fat condition, the 
gradual increase in weight must come from the food 
consumed. 

The formation of animal products, like milk, must be 
classed under this head, since the substances of which 
milk is composed first become a part of the animal, and 
are then converted into milk. 



ANIMALS. 117 

2. To repair Waste or supply Mechanical Force. — 
The particles of matter of which the bodies of animals 
are composed do not remain fixed and permanent. They 
are constantly being removed and replaced by new par- 
ticles. After a time the particles become old, and no 
longer useful, and new particles are formed from the 
food to take their place. 

A constant exchange is thus going on in all parts of 
the body, so that after a number of years a new body is 
formed, no part of the old remaining. The only excep- 
tion to this is the enamel upon the teeth, wdiich is believed 
to remain without change. 

This w^asting, or wearing away, of the substances of 
the body is increased by work or muscular exertion. 
The body is never at rest. When asleep, or when per- 
fectly quiet, the heart still beats to force the blood 
through the body, and the lungs arc regularly ex- 
panded to draw^ the breath. Every movement requires 
force, and this force is supplied either by food, or by 
particles of the body which must be replaced by the 
food. 

The force that drives a train of cars comes from the 
consumption, or burning, of fuel under the boiler ; so 
the force to produce motions of the body is obtained by 
chemical processes, w^hich either consume the elements of 
food or particles of the body which have been formed 
from food. 

3. To supply Heat. — The temperature of the l)odies 
of animals, w^hen in a healthy condition, is from 98° to 
100". It cannot be allowed to vary many degrees from 
this point, for any considerable time, without causing 
death. In cold and hot climates, in winter and in sum- 
mer, it must be kept constantly the same. When the 



118 THE PRINCIPLES OF AGRICULTURE. 

body becomes too warm, it is cooled by the evaporation 
of perspiration from the skin. 

As the air is generally cooler than the bodies of ani- 
mals, it is constantly cooling them. To take the place 
of the heat thus withdrawn, it is necessary that a new 
supply be constantly furnished in the system. This is 
produced by burning, or oxidizing, a portion of the food, 
or particles of the body. The oxygen for this process is 
obtained from the air through the lungs. 

The Composition of Foods. — The food of animals con- 
tains six different classes of sul)stances, as follows : — 

1. Water. — All articles of food contain more or less 
moisture. Hay and meal, which appear to be perfectly 
dry, contain from ten to twenty per cent, water. Succu- 
lent food, like green fodder and roots, may contain from 
seventy to ninety-five per cent, water. In addition to that 
contained in the food, the animal must drink enough to 
supply the wants of the system. 

2. Alhumiyioids. — The albuminoids of food, sometimes 
called jirotein, arc the parts containing nitrogen. They 
arc often called " flesh formers." They serve to form 
the flesh, or muscle, and the other nitrogenous parts of 
the body. 

The all)uminoids contain not only nitrogen, which is 
used in forming the muscles, but also other elements of 
an entirely different nature, which serve to supply heat 
or force. The albuminoids may thus be made to supply 
all the wants of the body ; but to confine animals to a 
diet composed entirely of nitrogenous food would be a 
wasteful practice. The albuminoids contain a larger 
proportion of nitrogen than animals require. After a 
sufficient quantity of such food has been consumed to 
supply enough nitrogen, it is necessary to consume an 



ANIMALS. 119 

additional quantity in order to obtain enough of those 
elements which supply heat and force. The nitrogen of 
this second quantity is wasted, since the animal has no 
further use for it. Heat and force may be more econom- 
ically supplied with foods containing less nitrogen. 

Amides are another class of substances containinsr 

o 

nitrogen. Tliey exist to some extent in various kinds 
of food, particularly in green or immature fodder plants, 
and in vegetables. They are less valuable than albumi- 
noids, since their nitrogen cannot be used to form the 
tissues of the body. They can only serve, Jike fats and 
carbo-hydrates, to produce heat and force. As they are 
found only in small quantities, and are comparatively of 
little importance, they have not generally been distin- 
guished from other elements in making an analysis of 
foods. 

Protein is a term used to include both the albumi- 
noids and the amides, or all parts of food which contain 
nitrogen. 

3. Fat. — ^The fatty parts of food correspond to the 
fats of animals. They are either oxidized to produce 
heat and mechanical energy, or are stored up in the sys- 
tem for future use. They are the most valuable class of 
substances for producing heat and energy. For these 
purposes they are worth about twice as much as the same 
amount of albuminoids. As they do not contain nitro- 
gen, they cannot be used in forming the tissues of the 
body. 

4. Oarho-hydrates. — The carbo-hydrates of food com- 
prise such substances as starch, sugar, cellulose, etc. 
They are composed of carbon, hydrogen, and oxvgen. 
The term hydrates is applied to them from the Greek 
word hudor, meaning water, because their hydrogen and 



120 THE PRINCirLES OF AGRICULTURE. 

oxygen when separated from the carbon would form 
water. 

They are either oxidized in the body to produce heat 
and energy, or are converted into fat. Tiiey are the 
least valuable of the digestible parts of food. Starch 
is an important part of these substances, and about two 
and one half i)arts of starch are required to produce the 
same effect as one part of fat. 

5. Fiber. — Most kinds of food contain more or less 
crude woody fiber, which is mostly indigestible and 
hence has little value as food. 

ot Ash. — The mineral substances in food, or those 
which would remain as ashes after burning, are also 
needed by the animal in about the same proportion as 
they exist in the average of the different varieties of food. 
When animals are confined to one particular kind of food, 
some of these substances may be deficient. Although 
the amount required is small, they cannot be dispensed 
with. Animals fed exclusively upon corn meal some- 
times lose the use of their legs from the want of sufficient 
mineral matter to form bones. 

On the page opposite is a table of some of the more 
common foods, with their average percentage composi- 
tion, as determined by chemical analysis. 

While the list gives the average results from a large 
number of separate tests, and must be approximately 
correct, it should be remembered that different samples 
differ widely in their nature. 

There would be a wide difference, for instance, be- 
tween the composition of early and late cut hay, or 
between unripe and mature corn fodder. 

While these figures may not accurately represent 
the composition of any particular sample of food, they 



ANIMALS. 



121 



will serve well enough as a general guide for practical 
purposes. 

Areratje Ptrcentiuje Composition of Articles of Food. 



Kinds of Food. 


Water. 


Ash. 


Albumi- 
noids or 
Protein. 


Fat. 


Carbo- 
hydrates. 


Fiber. 


Avera<?e hay .... 


11.82 


5.76 


8.51 


2.21 


41.38 


30.82 


Clover hay 


12.56 


6.10 


12.61 


2.48 


39.62 


26.63 


Timothy liay .... 


U.07 


4.06 


6.02 


2.16 


45.80 


30.89 


Oat straw 


9.02 


5.20 


3.51 


2.21 


36.09 


43.37 


Wheat straw .... 


(3.50 


6.96 


4.98 


1.49 


41.99 


38.08 


Rice straw 


3.66 


10.71 


4.68 


1.74 


50.90 


28.31 


Corn I'odder .... 


32 05 


4.32 


4.29 


1.24 


35.96 


22.14 


Fodder corn (green) 


80.98 


1.13 


1.62 


0.41 


10.62 


6.23 


Ensilage (Northern corn) 


70.55 


1.05 


2.65 


0.90 


18.84 


6.00 


Ensilage (Western corn) 


80.47 


1.35 


1.51 


0.70 


10.21 


5.77 


Cow-pea vines (dried) . 


n.05 


8.41 


15.68 


2.87 


42.17 


19.82 


Indian corn 


10.10 


1.55 


10.34 


5.13 


70.59 


2.29 


Oats 


10.94 


2.97 


11.38 


4.81 


60.05 


9.85 


Barley ...... 


10.92 


2.38 


12 39 


1.86 


69.88 


2.67 


Wlieat 


10.54 


0.80 


11.80 


2.11 


72.89 


1.80 


Rice 


14.80 


0.30 


7.50 


0.50 


76.00 


0.90 


Buckwheat 


12.60 


2.00 


10.00 


2.20 


64.50 


8.70 


Peas 


14.30 


2.40 


22 40 


2.00 


52.50 


6.40 


^Sorgluini (grain) . . . 


12.52 


1.80 


8.88 


3.65 


71.27 


1.88 


Wheat hran . . . . 


12.42 


5.68 


15.03 


3.74 


54.17 


8.96 


Wheat middlings . . 


12.00 


3.18 


14.83 


3.89 


61.55 


4.56 


Cotton-seed nieal> . . 


8.33 


7.25 


42.06 


13.24 


23.43 


5.69 


-Linseed meal (old process) 


9 20 


6.87 


31.53 


7.78 


36 34 


9.28 


Gluten meal .... 


9.15 


0.78 


29.88 


6.11 


52.62 


1.46 


Brewers' grains (dried) 


8.19 


3.58 


19.89 


5.56 


51.75 


11.03 


Apples 


83.1 


0.4 


0.4 




11.8 


4.3 


Pumpkins 


89.1 


1.0 


0.6 


b.i 


6.5 


2.7 


Potatoes 


75.0 


0.9 


21 


0.2 


20.7 


1.1 


Turnips 


92.0 


0.7 


1.1 


0.1 


5.3 


0.8 


Beets (sugar) .... 


87.0 


0.9 


2.0 


0.1 


9.2 


0.8 


Milk 


87.5 


0.7 


3.2 


3.G 


5.0 




Skimmed milk . . . 


90.0 


0.8 


3.5 


0.7 


50 




Buttermilk 


90.1 


0.5 


3.0 


1.0 


5.4 


, . 


Wliey 


92.6 


0.7 


1.0 


0.6 


5.1 





The Value of Foods. — The value of any food is deter- 
mined, not by the substances which it contains, but by 



122 THE PRINCIPLES OF AGRICULTURE. 

the amount of these substances that can be digested and 
]>ecome useful to the animal. 

There are but few articles of food of which all the 
albuminoids, fats, and carbo-hydrates can be thus di- 
gested. The indigestible part is of no value for food. 

The table on the opposite page gives the percentage of 
digestible albuminoids, fats, and carbo-hydrates contained 
in the different articles of food, and the value of one 
hundred pounds of each variety. 

In reckoning these values, the digestible albuminoids 
and fats are, according to the usual custom, regarded as 
worth 4i- cents per pound, and the digestible carbo- 
hydrates a& worth -^^ of a cent per pound. 

The results are, of course, only relative, and will vary 
according to the market value of the standard articles 
of food in any locality. If average hay is worth sixty- 
four cents per hundred pounds, or $12.80 per ton, then 
the other articles Avill be worth the sums given in the 
talDle as compared with hay. 

If in any locality, or any year, the market value of liay, 
corn, oats, or other articles commonly used, is greater or 
less, upon the average, than the table indicates, then the 
figures for all the articles mentioned must be increased 
or diminished accordingly. 

The table affords a general guide for selecting and pur- 
chasing foods, but it must not be depended upon for 
great exactness. No article of food can, in reality, have 
an absolute value of its own. The true value of any 
article as food depends upon its combination with other 
foods, the nature of the animal to which it is fed, and the 
purpose to be accomplished. In order to make an intel- 
ligent selection, it is necessary to understand what partic- 
ular kinds of food are needed in the given case. 



ANIMALS. 



123 



Percentage of Digestible Substances and Value of 100 Pounds of the Food. 




Albuminoids 




Carbo- 


Value of 
100 Pounds 


Kinds of Food. 


or 


Fat. 


hydrates, in- 




Protein. 




cluding Fiber. 




Average hay .... 


5.40 


1.00 


41.00 


$0.64 


Clover hay 


7.82 


1.49 


40.25 


0.77 


Timothy hay .... 


4.G7 


1.03 


41.25 


0.G2 


Oat straw 


L44 


0.G6 


42.62 


0.47 


Wheat straw .... 


0.85 


0.54 


37.70 


0.39 


Eice straw 


1.92 


0.52 


40.40 


0.46 


Corn fodder 


3.00 


0.93 


40.00 


0.53 


Fodder corn (green) . . 


L19 


0.31 


10.87 


0.16 


Ensilage (Western corn) 


1.10 


0.53 


10.99 


0.17 


Cow-pea vines (dried) . 


9.5G 


1.34 


37.02 


0.80 


Indian corn 


8.16 


4.36 


65 64 


1.13 


Oats 


8.46 


3.94 


46.11 


0.95 


Barley 


9.64 


1.86 


60.77 


1.04 


Wheat 


9.32 


1.79 


66.52 


1.05 


Kice 


5.92 


0.42 


70.71 


0.91 


Buckwheat 


7.70 


1.84 


49.21 


0.86 


Peas 


20.20 


1.70 


54.40 


1.44 


Sorghum (grain) . . . 


6.84 


2.99 


53.06 


0.90 


Wheat bran 


11.72 


2.58 


44.66 


1.02 


Wheat middlings . . . 


11.60 


2.68 


48.87 


1.06 


Cotton-seed meal . . . 


35.75 


11.05 


22.25 


2.25 


Linseed meal (old process) 


25.85 


7.08 


26.52 


1.66 


Gluten meal 


2.3.30 


3.85 


50.92 


1.6? 


Brewers' grains (dried) . 


14.52 


4.77 


37.41 


1.20 


Apples 


0.3 




12.9 


0.13 


Pumpkins .... 


0.4 


b.i 


7.1 


0.08 


Potatoes 


2.1 


0.2 


21.8 


0.30 


Turnips 


1.1 


0.1 


6.1 


0.11 


Milk 


3.2 


3.6 


5.0 


0.34 


Skimmed milk .... 


3.5 


0.7 


5.0 


0.23 


Buttermilk 


3.0 


1.0 


5.4 


0.22 


Whey 


1.0 


0.6 


5.1 


0.11 



Economy in Feeding. — There are two general precepla 
to be observed in connection with the economical feeding 
of stock : — 

1. Feed animals as much as they can digest without 
injuring their health. 

The profits of feeding stock come either from the 



124 THE PRINCIPLES OF AGRICULTURE. 

work which they are enabled to perform, or from growth 
and animal products. 

It requires a certain amount of food to maintain 
life. If just enough is fed to keep up the vital pro- 
cesses of the animal and prevent shrinkage of weight, 
it is evident that the cost of keeping is absolutely lost 
to the owner, imless, on accoimt of the variation of mar- 
ket prices, the animal is to be worth more at some 
future time. 

Whatever the animal consumes, digests, and assimi- 
lates, in excess of what is required to maintain life, will 
be a source of profit, as it will yield either force for 
work or animal products. 

Generally speaking, the more food the animal eats and 
digests, the greater is the profit, as the ratio of gain to 
the food consumed is greater. If it should require ten 
pounds of food i)er day to maintain the life of a certain 
animal, and three pounds of food in addition to produce 
a gain of one pound of flesh, then a ration of thirteen 
pounds of food would produce a daily gain of one pound 
of flesh. A ration of sixteen pounds would produce a 
gain of two pounds of flesh. In the former case the 
ratio of gain to food is one to thirteen, and in the latter 
case one to eight. 

This principle is limited, however, by the digestive 
power of the animal. Any excess of food above the 
quantity that can, be properly digested may lead to 
disease and loss. 

2. Feed a balanced ration. 

Animals should be supplied with food, the composition 
of which is in proportion to their needs. 

As the fats and carbo-hydrates of food are of a similar 
nature, and serve a similar purpose, it is customary, for 



ANIMALS. 125 

the sake of convenience, to class them together. The 
fats are reckoned as worth 2.44 times as much as carbo- 
hydrates ; hence, in combining the two, we multiply the 
number of pounds of fat by 2.44, and add the number of 
pounds of carbo-hydrates, giving what may be called the 
equivalent of carbo-hydrates contained in the food. 

The question of food for any animal, and for any pur- 
])ose, becomes a question of the proper proportion of 
albuminoids and carbo-hydrates. The animal needs, for 
its special requirements, a certain definite proportion of 
each. 

If we furnish a food containing too large a proportion 
of either albuminoids or carbo-hydrates, the excess of 
either above what is required to make up the proper pro- 
portion for the given purpose may be in part wasted, and 
may become an injury rather than a benefit to the ani- 
mal. The animal must consume a larger quantity of the 
food than would otherwise be necessary, in order to ob- 
tain the required quantity of that substance in wdiicli the 
food is most deficient. 

The Nutritive Ratio. — The nutritive ratio of a food is 
simply the ratio, or relation, between the quantity of di- 
gestible albuminoids, and of digestible carbo-hydrates or 
their equivalents, which it contains. Average hay, for 
instance, contains about eight times as much of digestible 
carbo-hydrates as of albuminoids, and hence the nutritive 
ratio of the food is as 1 to 8. 

The following tables give the nutritive ratio of the 
different kinds of food, and the number of pounds of 
digestible albuminoids and carbo-hydrates which should 
properly be contained in the daily ration of animals un- 
der different circumstances, for one thousand pounds of 
live weight. The quantity for animals weighing more or 



126 



THE PRINCIPLES OE AGRICLLTURE. 



less than one thousand pounds is found by increasing or 
diminishing the given amounts proportionately. Thus, a 
horse weighing twelve hundred pounds should receive 
one fifth more than the amounts given for one thousand 
pounds. 

Albuminoids, Equivalent of Carbo-hydrates, and Nutritive Ratio. 



Kinds of Food. 



Average hay 

Clover hay 

Timothy liay 

Oat straw 

Wlieat straw 

Rice straw 

Corn fodder 

Fodder corn (green) . . 
Ensilage (Western corn) . 
Cow-pea vines (dried) . . 

Indian corn 

Oats 

Barley 

Wheat 

Rice 

Buckwheat 

Peas 

Sorghum (grain) . . . 

Wheat bran 

Wheat middlings . . . 
Cotton-seed meal . . . 
Linseed meal (old process) 
Gluten meal . . . . . 
Brewers' grains (dried) . 

Apples 

Pumpkins 

Potatoes 

Turnips 

Milk 

Skimmed milk .... 

Buttermilk 

Whey 



Digestible 



Albuminoids. 



5.40 

7.82 
4.67 
L44 
0.85 
L92 
3.00 
1.19 
1.10 
9.56 

8.16 

8.46 

9.64 

9.32 

5.92 

7.70 

20.20 

6.84 

11.72 

11.60 

35.75 

25.85 

23.30 

14.52 

0.30 
0.40 
210 
1.10 

3 20 

3.50 
3.00 
1.00 



Carbo-hydrates 
with Fat X 2.44. 



43 44 
43.89 
43.76 
44.23 
39.02 
41.67 
42.27 
11.63 
12.28 
40.29 

76.28 
55.72 
65.81 
70.89 
71.73 
53.70 
58.55 
60.90 
50.96 
55.41 
50.68 
43.80 
60.26 
49.05 

12.90 
7.34 

22.29 
6.34 

13.78 
6.71 

7.84 
6.56 



Nutritive 
Ratio. 



to 8 

to 5.6 
to 9.4 
to 30.7 
to 45.9 
to 21.7 
to 14 
to 9.8 
to 11.2 
to 4.2 

to 9.3 

to 6.6 

to 6.8 

to 7.7 

to 12.1 

to 7 

to 2.9 
8.9 

to 4.8 

to 4.8 

to 1.4 

to 1.7 

to 2 6 

to 3.4 

to 4.8 
to 18.4 
to 10.6 
to 5.8 

to 4.3 

to 1.9 

to 26 

to 6.6 



ANIMALS. 



12T 



Food required for different Animals, foi 


• 1,000 Pound 


s, live weight. 






Digestible 




Animals in different 


Digestible 


Carbo-hydrates 


Nutritive 


Circumstances. 


Albuminoids. 


with equivalent 
of Fat. 


Ratio. 




lbs. 


lbs. 




Horses in light work . . 


1.8 


12.6 


1 to 7 


Horses in heavy work 




2.8 


15.5 


1 to 5.5 


Oxen at rest . . . , 




0.7 


8.3 


1 to 12 


Oxen at work . . . 




2.4 


14.4 


1 to 6 


Oxen fattening . . . 




3.0 


16.5 


1 to 5.5 


Cows in milk . . 




2.5 


18.5 


1 to 5.4 


Growing cattle . . . 




1.6 


12.7 


1 to 8 


P'attening swine . . 




4.0 


24.4 


1 to 6 


Fattening sheep 




3.5 


15.6 


1 to 4.5 



Rations. — To make up a balanced ration, we have 
simply to reckon the quantit}' of digestible albuminoids 
and carbo-hydrates contained in a certain amount of the 
different articles of food in question, varying the quan- 
tity of each article to meet the wants of the case. 

If, in making up a trial combination, we find we 
have too large a proportion of albuminoids, then we 
should increase the proj^ortional part of those articles 
in the ration which are more largely composed of carbo- 
hydrates, and vice versa. 

Strict accuracy is not necessary. If the result is within 
a fraction of what is theoretically required, it is near 
enough for practical purposes. 

The question whether the ration is properly balanced 
should always be considered in making a combination of 
foods. It is not always necessary, however, to follow 
the theory strictly. Some allowance may be made for 
market prices. 

If either the nitrogenous foods or the carbonaceous 
foods are relatively much cheaper in the markets, a 
larger proportion of the cheaper class may be admitted 



V2S 



THE PRINCIPLES OF AGRICULTURE. 



into* the ration for the sake of economy. The difference 
in cost may be sufficient to overcome the loss caused by 
feeding an incorrect ration. 

The following sample rations will illustrate the 
method : — 

Ration for a Cow, weighing 1,000 Pounds, giving Milk. 



Daily Ration. 


Digestible. 


Albuminoids 


Carbo-hydrates. 


Englisli hay, 15 lbs. furnishing .... 

Ensilage, 15 lbs. furnisliing 

Cotton-seed meal, 2 lbs. furnishing . . 
Wheat midaiings, 7 lbs. furnishing 

Total furnished 

Total required 

Ratio furnished 

Ratio required , . . 


lbs. 

0.81 
0.17 
0.72 
0.81 


lbs. 

6.52 
1.84 
1.01 

3.88 


2.51 

2.5 


13.25 
13.5 


1 to b.?> 
1 to 5.4 



Ration for a Horse, iceighing 1,200 Pounds, at light WorJc. 



Daily Ration. 


1 
Digestible. 


Albuminoids. 


Carbo-hydrates. 


Timothy hay, 10 lbs. furnishing . . . 
Oats, 18 " " ... 
Corn, 2 " " ... 

Total furnished 

Furnished for 1,000 lbs 

Required for 1,000 lbs 

Ratio furnished 

Ratio required 


lbs. 
47 
1.52 

0.10 


lbs. 

4.38 

10.03 

1.53 


2.15 

1.8 
1.8 


15.94 

13.3 

12.6 


1 to 7.4 

1 to 7 



ANIMAJLS. 

Ration for a Fattening Hog, weighing 200 Pounds. 



129 



Daily Ration. 


Digestible. 


Albuminoids. 


Carbo-hydrates. 


Corn meal, 5 lbs. furnishing 

Skimmed milk, 6 lbs. furnishing . . . 
Chopped clover hay, 2 lbs. furnishing. . 

Total furnished 

Furnished for 1,000 lbs 

Required for 1,000 lbs 

Ratio furnished 

Ratio required 


lbs. 

0.41 
0.21 
0.16 


lbs. 

3.81 
0.40 

0.88 


0.78 
3.90 
4.0 


5.09 
25.45 
24.4 


1 to 6.5 
1 to 6 



Variety of Food. — In order that animals may be 
always kept in a healthful and thriving condition, they 
should be supplied with a variety of food. Although a 
single kind of food, or some particular combination of 
two or more kinds, may contain the albuminoids and 
carbo-hydrates in proper proportion, it is unwise to con- 
fine an animal to one special diet for a long time. The 
appetite and digestion are improved by furnishing a 
greater variety. 

In computing a ration, we do not take into account 
the mineral substances contained in it. Although the 
quantities of these required are small, they are essential 
to perfect health. A particular ration may not contain 
sufficient quantities of all of these, and after a time the 
lack may cause injurious results. By furnishing a greater 
variety, or changing the ration frequently, we may keep 
the various wants of the animal more perfectly supplied. 
The Manurial Value of Food. — In selecting food for 
animals upon the farm, the cost of the food and its value 
for supporting animals are not the only points to be 

Wins. Agr. — 9 



130 



THE PRINCIPLES OF AGRICULTURE. 



considered. We should also take into account its ma^ 
nurial value, or value as a fertilizer. 

Any kind of food has a certain value as a fertilizer, 
and may be used directly for that purpose if it is not 
too expensive. 

Cotton-seed is extensively used in this way in the South. 

The manurial value, as in ordinary fertilizers, is de- 
termined by the amount of nitrogen, phosphoric acid, 
and potash contained. 

Tlie following table shows the number of pounds of 
the three substances contained in one ton of each variety 
of food, and the manurial value of a ton. This value is, 
of course, variable, depending upon the market value of 
the three substances for the locality and the season. 



Manurial Substances in a Ton of 


Food, and their Value. 


Kinds of Food. 


Nitrogen. 


Phosphoric 

Acid. 


Potash. 


Value in 
a Ton. 




lbs. 


lbs. 


lbs. 




Cotton-seed meal . . . 


124.0 


59.0 


42.0 


$26.66 


Linseed meal . . 






90.0 


39.2 


29.4 


19.01 


Wheat bran . . 






44.0 


64.6 


29.6 


13.69 


Beans .... 






82.0 


28.2 


24.0 


16.18 


Peas 






72.0 


17.6 


19.6 


13.91 


Oats 






41.2 


12.4 


9.0 


8.03 


Barley .... 






34.0 


14.0 


9.8 


7.10 


Wheat .... 






37.6 


16.0 


10.8 


7.84 


Indian corn . . 






33.2 


12.2 


7.2 


6.65 


Buckwheat ... 






28.8 


8.8 


4.2 


5.52 


Average hay . . 






31.0 


7.6 


33.6 


7.25 


Timothy hay . . 






31.0 


13.6 


34.4 


7.77 


Dead ripe hay 






24.0 


5.8 


10.0 


4.80 


Clover hay . . . 






39.4 


11.2 


39.0 


9.15 


Bean straw . . . 






20.0 


8.2 


51.8 


6.45 


Oat straw . . . 






10.0 


5.0 


20.8 


3.04 


Wheat straw . . 






9.6 


5.2 


11.6 


2.53 


Corn fodder . . 






16.0 


15.2 


66.4 


7.10 


Potatoes 


6.8 


8.6 


11.2 


1.94 


Turnips 


3.6 


1.2 


5.8 


0.96 



ANIMALS. 131 

Differences in the quality of the food will also cause 
variation, as in reckoning the feeding value. 

The figures given are obtained by reckoning the nitro- 
gen at sixteen cents per pound, the phosphoric acid 
at eight cents, and the potash at five cents. 

The values of these substances are reckoned the same, 
in whatever food they are found. There is, however, 
some difference in point of fact, since in some articles 
of food they are in a more available condition than in 
others, and can be made more immediately serviceable 
as fertilizers. 

The Value of Manure from Food. — To determine the 
real value of the manure from different kinds of food, a 
deduction must be made from the total manurial value 
for certain losses that occur. 

1. We must deduct the amount which the animal re- 
moves from the food in digestion. This may be reckoned 
upon the average at fifteen per cent. 

2. The three su])stances are not g nerally so valuable 
in stable manure as in commercial fertilizers, because 
they are not so largely available at first, and are subject 
to greater losses before they can be used for plant food. 
Probably twenty per cent, should be deducted on this 
account. 

It must also be remembered that, in addition to these 
deductions, there is always more or less loss from fer- 
mentation and drainage ; but this is so variable that it 
cannot be definitely stated. It can only be estimated in 
individual cases, after a knowledge of the facts involved. 

All articles of food fed to stock upon the farm have 
thus a double value : a feeding value, determined by the 
digestible albuminoids and carbo-hydrates ; and a manu- 
rial value, determined by the amount of nitrogen, phos- 
phoric acid, and potash in the manure. 



132 



THE PRINCIPLES OF AGRICULTURE. 



The following table gives these two values separately 
and combined : — 

Double Value of Food, per Ton. 



Kinds of Food. 



Value for 
Feeding. 



Value of 
Manure. 



Double 
Value. 



CottoH-seed meal 
Linseed meal . 
Wheat bran . . 
Peas .... 
Oats .... 
Barley .... 
Indian corn . . 
Buckwheat . . 
Average hay 
Timothy hay . 
Clover hay . . 
Oat straw . . 
Corn fodder . . 
Potatoes . . . 
Turnips . . . 



$45.00 

33.20 

20.40 

28.80 

19.00 

20.80 

23.00 

17.20 

12.80 

12.40 

15.40 

9.40 

10.60 

6.00 

2.20 



$18.13 
12.93 
9.31 
9.46 
5.46 
4.83 
4.52 
3.75 
4.93 
5.28 
6.22 
2.07 
4.83 
1.82 
0.65 



$63.13 
46.13 
2971 
38.26 
24.46 
25.63 
27.52 
20.95 
17.73 
17.68 
21.62 
11.47 
15.43 
7.32 
2.85 



The True Cost of Food. — In estimating the real expense 
involved in the food furnished to stock, the value of the 
food as a source of fertility to the farm should be de- 
ducted from its cost or market value. The results will 
vary widely with the variation in market prices. 

The following table will illustrate this point : — 

Cost of Food in Excess of Value of Manure. 



Kinds of Food. 



Cotton-seed meal 
Linseed meal . 
Wheat bran . . 
Oats .... 
Indian corn 
Average hay 
Clover hay . . 
Oat straw . . 



Cost per 
Ton. 



$28.00 
29.00 
20.00 
25.00 
18.00 
12.00 
12.00 
5.00 



Value of 
Manure. 



$18.13 
12.93 
9.31 
5.46 
4.52 
4.93 
6.22 
2.07 



True Cost 
of Feed. 



$ 9.87 

16.07 

10.69 

19.54 

13.48 

7.07 

5.78 

2.93 



ANIMALS. 



133 



Digestion. — The purpose of digestion is to dissolve 
food and change its nature, preparing it to enter tlic 
blood, and to sustain the life and growth of the body. 
As the food of plants is slowly prepared to enter the sap 
by chemical processes in the soil, so the food of animals 
is prepared in their digestive organs to enter the blood 
by similar processes, although much more rapidly. 

The Mouth. — The process of digestion begins in the 
mouth. The food is not only ground into a fine condi- 
tion by mastication, 
and better prepared 
for chemical action, 
but is also mixed with 
the saliva. 

This is a liquid 
consisting mostly of 
water, but containing 
substances suited to 
produce some chemi- 
cal action . upon the 
food. It is secreted, 
or separated from the blood, by a number of organs 
called glands, situated in different parts of the mouth. 
As the blood passes through these glands, the saliva is 
taken from it and poured into the mouth as it is needed 
to moisten the food. It is formed quite rapidly while 
the animal is eating. It is said to be produced in the 
mouth of a horse or an ox, at such times, at the rate of 
four quarts per hour. 

The Stomach and Intestines. — After the food which has 
been moistened by the saliva passes into the stomach, it 
is mixed with other liquids, which are withdrawn from 
the blood and poured into the stomach. 




One of the Salivary Glands. 



134 THE PRINCIPLES OF AGRICULTURE. 

The mixture is kept constantly in motion by the ac- 
tion of the muscular walls of the stomach, until the food 
becomes softened or dissolved. It then passes into the 
intestines. 

The intestines consist of a long tube folded together 
so as to occupy a small space. The portion nearest the 
stomach is the smaller in diameter, and is called the 
small intestine. The remainder is larger, and is called 
the large intestine. 

The intestines of an ox have an average length of 
about 150 feet, and those of a sheep or a pig of about 
90 feet. 

In the intestines, the food is still further mixed with 
chemical liquids, and converted into different forms. As 
it is thus rendered suitable for nourishment, either in the 
stomach or the intestines, it is absorbed by the mem- 
branous lining, and passes through minute tubes called 
the lacteah into the blood-vessels, to be carried by the 
circulation of the blood to all points of the system where 
it ij needed. 

The Stomachs of Eiitninants. — Such animals as the cow, 
the sheep, and the goat are called ruminants^ because 
they ruminate^ or " chew the cud." 

As these animals naturally live upon food containing 
large quantities of hard, woody fiber, their digestive 
system is different from that of other animals whose 
food is more concentrated and more easily digested. The 
chief point of difference is, that, in addition to the reg- 
ular stomach of other animals, the ruminants have three 
preliminary stomachs in which coarse food is prepared 
to enter the stomach proper. 

The first stomachy or paunch (/>)? i^fo which coarse 
food first passes as it is swallowed, is very large. It is 



ANIMALS. 



135 



several times as large as the other three stomachs com- 
bined. In a large ox it contains about sixty gallons, and 
occupies nearly the whole length of the left side of the ab- 
domen, or internal cavity of the body back of the lungs. 

The second stomach (b) is in reality only a part of the 
first, as there is a free passage connecting the two. The 
membrane lining its inte- 
rior is curiously formed in- 
to an arrangement of cells 
like honeycomb. 

The third stomach (/) 
is provided with a great 
number of hard, hooked 
projections, which hold the 
food until it has been ren- 
dered fine enough to pass 
through into the fourth 
stomach. 

The fourth stomach (c) is 
the true digesting stomach, 
corresponding to the stomach of the horse or the pig. 

The gullet, or tube (o) through which the food passes 
from the mouth to the stomach in swallowing, is, in 
ruminants, provided at its lower end with a peculiar 
canal, by which the food as it is swallowed may pass 
either into the first two stomachs on the one hand, or 
on the other hand into the third stomach. All food of 
a coarse, fibrous nature generally passes into the first 
two stomachs, but that which is fine and soft, requiring 
no further preparation, may pass at once into the third 
and fourth stomachs. 

Rumination. — Rumination, or the chewing of the cud, 
is a very interesting process. As the first stomach is 




stomach of a Ruminant. 



136 THE PRINCIPLES OF AGRICULTURE. 

well filled, partly with solid food, and partly with liquids, 
a small quantity of the food near the lower entrance to 
the gullet is floated upward by the liquid into the mouth 
by a slight contraction of the stomach. The animal 
grasps the solid part in its mouth, swallows the liquid, 
and proceeds to masticate the food, reducing it to a finer 
and softer condition. As this is again swallowed, such 
parts as are sufficiently fine and soft pass into the third 
and fourth stomachs, and the remainder passes into the 
paunch to be returned to the mouth a second time. 

In order that rumination may go on, it is necessary 
that the paunch be quite well filled, and that there shall 
be enough liquid to separate and float the solid food 
freely. 

Ruminants, when supplied with sufficient water, are 
able to live without food for a long time, as they are 
able to make use of the large store of food in the 
paunch, which is gradually reduced to a fine condition, 
and passed along to the fourth stomach and intestine (<i) 
for digestion. 

The Blood. — The blood, in its circulation, is the car- 
rying system of the animal body. The tubes through 
which it passes become so small by subdividing that the 
blood is practically brought in contact with, and moistens, 
all parts of the system. 

As the substances formed from the food pass from the 
stomach and intestines into the blood, they are imme- 
diately carried forward with the current and distributed 
through the system. 

The blood is forced along by the pumping action of 
the heart. On leaving the heart, it passes into large 
tubes called arteries (a, a, a). These s©on begin to sub- 
divide into smaller arteries, and these again into still 



ANIMALS. 



137 



smaller, until they become a multitude of minute tubes, 
called capillaries^ passing through every part of the body. 
At length these again gradually unite in veins (v, v, v)^ 
throuo-h which the blood is returned to the heart. It is 




Arteries, Capillaries, and Veins. 



then sent out through another set of tubes, which con- 
duct it through the lungs, where it is brought in con- 
tact with the air taken into the lungs in breathing, 
becomes purified, returns to the heart, and starts again 



on its original course. 



138 THE PRINCIPLES OF AGRICULTURE. 

The blood consists of a colorless fluid, containing an 
immense number of little flattened disks, called corpus- 
cles. Most of these are red, and give the blood its color. 

The purpose of these disks seems to be to absorb oxy- 
gen from the air in the lungs, and carry it through the 
body, until it is needed to oxidize the elements of food in 
the blood, or the tissues of the body. 

As the disks return from the lungs they have a bright 
red color, which is supposed to be due to the presence of 
oxygen that they have absorbed. On returning to the 
heart, after passing througli the body, they assume a 
purple shade. 

The elements of food in the blood are burned, or ox- 
idized, by uniting with the oxygen of the corpuscles, pro- 
ducing animal heat or force. Particles of the body are 
also oxidized and replaced by new particles. 

Excretion. — Tlie blood not only brings together food 
and oxygen to produce this oxidation, but carries away 
the waste products. 

When the carbo-hydrates and fats of food are burned 
in the system, the result is carbonic acid and water. 
When nitrogenous substances are burned, not only car- 
bonic acid and water are produced, but also certain 
salts, the most important of which is called urea. 

Carbonic acid escapes from the blood partly through 
the skin, but mostly through the lungs ; urea and other 
salts, through the kidneys ; and water, through the skin, 
lungs, and kidneys. 

The Nature of Animals. — An animal upon the farm may 
be regarded as a kind of machine, capable of performing 
a certain amount of work. 

This work consists in converting food into flesh, milk, 
wool, etc., or into mechanical force, for the service of 



ANIMALS. 139 

man. The better the animal, the better the work 
accomplished. 

A locomotive engine supplied with water and fuel is 
able to draw a train of cars. Another engine, more per- 
fectly constructed, but supplied with the same amount of 
fuel, might produce force enough to draw a train much 
heavier. The same is true in feeding animals. Econ- 
omy and profit in stock husbandry require that poor ani- 
mals shall be discarded, and that the crops of the farm 
shall be fed only to such as are able to render good 
returns. 

Health. — The health or thrift of animals is a matter 
that should receive careful attention. As good health 
promotes comfort, we should care for the health of our 
animals on the ground of humane treatment. But the 
question has a practical bearing also upon the profits of 
feeding. The more vigorous the health, the greater the 
returns for the food. One animal may thrive and in- 
crease in weight upon food with which another, in less 
vigorous health, would grow poor. 

One cow with the same food as another may produce 
much more milk, on account of being in better health, 
and possessing greater power to digest food. 

Breeds. — By the law of heredity, animals tend to trans- 
mit to their young their own qualities and peculiarities. 
It is therefore important, in selecting young animals 
to be raised, to make choice of those descended from 
animals known to possess desirable qualities. 

The common pure breeds are simply families of ani- 
mals whose ancestors were selected for their excellence 
in certain directions. 

The advantage of thoroughbred animals consists in 
the fact that they possess certain particular qualities in 



140 THE PRINCIPLES OF AGRICULTURE. 

a higher degree than others. An opportunity is offered 
to choose such breeds as are best adapted to the purpose 
required. One breed of cows may have a natural ten- 
dency to take on fat, or produce beef, while another will 
tend to produce milk. One breed of horses is adapted 
for speed, and another to draw heavy loads. Some 
breeds of pigs will fatten rapidly while young, and 
others not until they become older and larger. 

Economy requires that we select such breeds of the 
different animals as possess in the most marked degree 
the peculiarities required for the special purpose to which 
they are devoted. 

Care. — The general care and treatment of animals is 
as much a source of profit as a matter of sentiment. To 
shelter stock in warm stables in w^inter prevents a loss of 
animal heat. The amount of food required to keep the 
body warm depends largely upon the question how fast 
the body is cooled from without. When stock is kept in 
tightly built stables, the warmth from the body is not re- 
moved by drafts, but remains to elevate the temperature 
of the air in the stable, and so prevents a rapid cooling 
of the animal. 

Food that is not needed to produce animal heat is free 
to serve other purposes. The extra food required to 
keep up the temperature of a herd of animals in a cold 
apartment would, in a single winter, pay the cost of ren- 
dering the apartment tight and warm. 

Kindness. — There is profit as well as sentiment in 
" kindness to animals." The digestive and nutritiTC pro- 
cesses are largely influenced by the condition of the ner- 
vous system. Animals which are disposed to fight or 
annoy each other will not thrive so well as if kept apart, 
or in more congenial company. A horse with an irrita- 



ANIMALS. 141 

ble driver will grow poor, while with kinder treatment 
and the same feed and work he might maintain a good 
condition. 

It is true of the lower animals, as of man, that " it is 
worry, and not work, that kills." Many a farmer reduces 
the income from his stock by abusive treatment. 

Conclusion. — A knowledge of the principles of agricul- 
ture is simply a knowledge of some of the laws of nature, 
which have a divine origin. 

To understand these principles, and to observe them 
in practice, is simply to place ourselves in conformity 
with natural laws which are based upon the strictest pro- 
priety and economy. 

Success and failure in agriculture turn upon this 
point. The heedless and indifferent can never receive so 
large* a share of the bounties of our mother Earth as 
those who are on the alert to catch the lessons which 
nature teaches, and to profit by them. " If ye be willing 
and obedient, ye shall eat the good of the land." 



QUESTIONS. 

What are the two forms of life? What is the chief purpose of vege- 
tation ? Ar^ the bodies of animals composed of the same materi- 
als as plants? What is the difference between herbivorous and 
carnivorous animals ? What is the nature of the process of animal 
life? 

Name the different classes of substances in the body of an animal. 
What proportion of the body is water ? What is the use of water 
in the body ? Wliat parts of the body are composed of nitrogenous 
substances? Where is fat to be found in the body? Explain 
the different kinds of fat. What elements are included in the 
" ash " ? 

What are the different purposes of food ? What use do young ani- 
mals make of food different from mature animals ? Do the bodies 



142 THE PRINCIPLES OF AGRICULTURE. 

of mature animals remain constantly the same ? What is the 
source of muscular power ? How is animal heat supplied by food ? 
At what temperature must the body be kept ? How is it cooled 
when too warm in hot weather ? 

Of what substances is food composed ? Are any kinds of food abso- 
lutely dry ? How much moisture do some succulent foods contain ? 
What are the albuminoids of food ? What parts of the body do 
they form ? May they be used to produce heat ? Is this an eco- 
nomical use of them? Name some kinds of food which are espe- 
cially rich in albuminoids. Could an animal hve entirely upon 
albuminoids ? What are the amides ? In what kinds of food are 
they chiefly found? How do they differ from albuminoids ? What 
is protein ? What uses are made of the fats of food ? Why can 
they not be used for constructing the tissues of the body ? Name 
some of the different kinds of fats. Name some articles of food 
which are rich in fats. 

What are the carbo-hydrates ? Why are they so called ? What use 

is made of them ? How valuable are they ? Could an animal live 

entirely upon fats and carbo-hydrates ? Name some kinds of food 

which are largely composed of carbo-hydrates. Has woody fiber 

^ny value as food ? 

WnS,t is meant by the " ash " of foods ? Of what substances is the 
ash composed ? Are these substances essential in the food of ani- 
mals ? Name some kinds of food which are especially rich in 
albuminoids. Name some in which the fats and carbo-hydrates 
preponderate. 

Upon what does the value of food depend ? Has the indigestible part 
any value ? Name some kinds of food which are wholly digestible. 
Name some kinds of which a large part is indigestible. 

What two rules should be generally followed in feeding stock ? Why 
should animals generally be fed as much as they can digest? Is 
there danger in feeding too much ? What is meant by a " balanced 
ration"? Why is a part of a ration that is not well balanced 
wasted ? 

What is the nutritive ratio of a food ? How is a balanced ration made 
up ? Name articles of food which might be combined to form a 
proper ration for oxen at work. For fattening sheep. What is 
the advantage of furnishing a variety of food ? 

What is meant bv the " manurial value " of food? How is this value 



ANIMALS. 143 

determined ? Is the manurial value of the same variety of food 
always the same ? Are the manurial substances of the same value 
in whatever food they are found ? Name articles of food which 
have a high manurial value. Wha is the difference between the 
manurial value of food, and the value of the manure from the food ? 
What items must be deducted from the one to obtain the other? 
What circumstances increase and diminish this difference ? 

What are the two values of food ? How is the true cost of food to be 
reckoned in farming ? Name articles which cost but little accord- 
ing to this method of reckoning. 

What is the purpose of digestion ? Do plants digest their food, like 
animals? How does digestion begin in the mouth? What is the 
saliva ? How fast is it formed ? Explain the action of the stom- 
ach. Describe the intestines. How long are they ? What becomes 
of the food after it is digested ? 

Name the animals called " ruminants." Why is their digestive 
system different from that of other animals? What is the chief 
difference? Describe the first stomach. What is the second 
stomach ? 

What service does the third stomach perform? Which stomach 
corresponds to that of other animals ? Into which stomach does 
the food first pass, when swallowed ? In what way is the " cud " 
brought to the mouth ? Into which stomach does it pass when 
swallowed again ? What may be the difficulty with animals unable 
to chew the cud ? Why are ruminants able to live longer without 
food than other animals ? 

What is the use of the blood ? In which parts of the body is it to be 
found? Describe the system of tubes through which the blood 
passes. Why does it pass through the lungs ? Of what does the 
blood consist ? What is the purpose of the corpuscles ? From 
what does blood derive its color ? Why is the color different in 
different parts of the body ? 

What other office does the blood fill besides conveying nourishment 
to the body ? Name the other waste products of the body besides 
undigested food. Name the different methods by which they 
escape from the body. 

How does an animal resemble a machine ? Why is one animal more 
profitable than another for a given purpose ? For what two rea- 
sons should the health of animals be cared for? 



144 THE PRmCIPLES OF AGRICULTURE. 

What is the origin of different breeds of animals ? What advantage 
is there in thoroughbred animals? What advantage is there in 
a variety of breeds ? Why is it profitable to provide shelter for 
stock ? For what two reasons should animals receive kind treat- 
ment? How does unkind treatment reduce the income from 
animals? 



GLOSSARY. 



Al-bu'mi-noids . 

Al'ka-li 

Arka-line .... 
Al-lu'vi-al .... 



Am'ides 

An-ti-cy'clone . . 



Ap'a-tite . . . 
Assimilate . 
Cal-ca're-ous 

Calyx 

Capll-la-ries . 



Car-bo-hy'drates 

Car-bo-na'ceous . 
Car-niv'o-rous . . 
Cellu-lose .... 



Con-glom'er-ate . . 

Corolla 

Cor'pus-cles . . . , 
Cot-y-le'don . . . . 

Cy'olone 

De-com-po-si'tion. 



A class of substances in foods which contain the 
most of the nitrogen. 

A class of bases including ammonia, soda, potash, 
etc. 

Resembling or possessing the qualities of the al- 
kalies. 

Pertaining to a river. Alluvial deposits are depos- 
its from the washing of rivers. 

A class of substances contained in foods. 

The opposite of cyclone. Winds moving in the 
opposite direction from those of a neighboring 
storm, or cyclone. 

A greenish mineral composed of phosphate of lime. 

To convert the food into the substances of .the body. 

Consisting of lime, or containing lime. 

The outer covering of a flower. 

The smallest tubes through which the blood passes 
in its circulation. 

A large class of substances in foods, composed of 
carbon, hydrogen, and oxygen. 

Containing carbon, or composed of carbon. 

Feeding upon the flesh of animals. 

A substance of which the membranes of cells of 
plants are largely composed. 

Heaped together. 

The inner covering of a flower. 

Minute, disk-shaped particles, floating in the blood. 

One of the two seed leaves of a plant which first 
appears. 

A storm, the winds of which blow in a circuit. 

Decay, or a chemical change into other substances. 

(145) 



146 GLOSSARY. 

Dis-in-te-gra'tion . Destruction, or separation into parts. 
Ex-cre'tion Throwing off useless matter from the animal 

system. 

Gla'cier An immense mass of moving ice. 

Her-biv'o-rous . . Eating herbs. Living upon vegetation. 

Hu'mus A dark or brown substance, common in soils. 

tn com-bus'ti-ble . Not capable of being burned. 

t'so-bar A line indicating the points where the height of the 

barometer is the same. 
I'so-therm .... A line indicating points where the temperature is 

the same. 
Lac'te-als Passages through which blood is conveyed from 

the stomach and intestines to the blood-vessels. 
Le-gu^mi-nous . . Pertaining to a class of plants, including peas, 

beans, clover, etc. 
Ni-tri-fi-ca'tion . . A natural process by which nitrates are formed ia 

the soil. 
Ni-trog'e-nous . . . Pertaining to nitrogen, or containing nitrogen. 

Ole-in The oily part of foods in the animal body. 

Parmi-tin One of the kinds of animal fat. 

Pet'ri-J5ed Converted into stone, or into a substance like stone. 

Plu'mule The first bud, or ascending part of a young plant. 

Pro'te-in Those parts of food which furnish nitrogen. 

Ru'mi-nate To chew the cud. 

Ru'mi-nant .... An animal that chews the cud. 

Sal'i-va-ry Producing saliva. 

Se-crete' To separate ; as to separate fluids from the blood. 

Ste'a-rin One of the hard kinds of fat in the animal body. 

Sto'ma-ta Minute mouths or openings on the surface of 

leaves. 

TulDer-ous Covered with or containing tubers. 

U're-a One of the waste substances of the system, sepa- 
rated from the blood by the kidneys. 



INDEX. 



A. 

Page 

Absorbing power of roots ... 08 

Absorption, of water by plants . 62 

of ammonia by plants . . 02 

Acids . . . .' 12 

Acids, bases, and salts .... 12 

Adhesion 14 

Age of the earth 27 

Agriculture, effect of ... . 78 

Air, composition of 41 

necessary for roots . . . 101 

purified by plants .... 61 

Albuminoids 118 

Alkalies 13 

Alum 17 

Alumina 23 

Aluminium 23 

Alluvial soil 32 

Amides 119 

Ammonia .... 11, 13, 18, 21 

absorbed by foliage ... 62 

carbonate of 82 

formation of .... 81, 82 

Amnionic chloride 13 

Animal heat 117, 140 

Animals, remains of ... . 37 

breeds of 139, 140 

care of ] 40 

composition of bodies of . . 114 

health of 138 

kindness to 140 

nature of 138 

yoyng ........ 116 

Apatite 85 

Application of fertilizers ... 89 

Application of manure .... 94 

Arteries, the 136, 137 

Artificial fertilizers S3 



Page 
Ash of animal bodies .... 116 

of food 120 

Atmosphere 31, 41 

weight of 42 

Atomic theory 8 

Atoms 8, 11 



B. 

Balanced ration .... 124, 125 

Barometer 43, 44 

Bases 12, 13 

Beans 62 

Beets 63 

Biennial plants 62 

Blight 69 

Blood, the 136, 137, 138 

Blue litmus 66 

Bodies of animals . . 114, 115, 116 

Bones as a fertilizer 84 

Bone-black ....... 84 

Bowlders, origin of 34 

Breathing 137 

of plants 61, 62 

Breeds of animals . . . 139, 140 

Breezes 45 

Brimstone 24 

Buttercups, roots of 63 

C. 

Calcareous soil 39 

Calcium 23 

carbonate 23 

hydrate 86 

oxide 19,86 

phosphate !S. 

Calyx 74 

(147) 



148 



INDEX, 



Page 

Canada thistles 63 

Cane sugar 12 

Cap of roots 64 

Capillaries, the 137 

CapiUary attraction 67 

of roots 68 

in plants 71 

Carbo-hydrates .... 119, 120 

Carbon 21 

from the air 60, 61 

Cai-bonate of ammonia ... 82 

Carbon dioxide 19 

Carbonic acid . 13, 14, 18, 19, 20, 41 
absorbed by plants ... 61 
in the animal system . . . 138 

in the soil 101 

Carboniferous vegetation ... 39 

Care of animals 140 

Carnivorous animals .... 114 

Carrots 63 

Caustic potash 23 

Caustic soda 23 

Cells 68 

form of 70 

growth of 69 

of a potato 69 

of ripe fruit 69 

Cellulose 60 

Charcoal 21 

as a filter ....... 14 

Chemical action 11 

in soil 80 

Chemical affinity 9 

Chemical equations 12 

Chemicals, use of 88 

Chewing the cud .... 135, 136 

Chlorate of potash 23 

Chloride of potash . . . . 13, 85 

Chlorine 22 

Circulation of the blood . . . 136 

Clay 22 

Clayey soil 38 

Climate 50, 51 

Clouds 47 

Clover 62, 63, 73 

roots 64 

Coal, origin of 37 

Cohesion 14 

Cold wave 49 

Combustible matter 18 



Page 

Combustion ....... 20 

Composition of foods .... 118 

of soil 77 

Continents, formation of . . . 27 

Cooling of the body .... 118 

Coral reefs 37 

Corn meal, effects of ... . 120 

Corpuscles 138 

Cotton 70 

fiber 73 

Cranberry plants 101 

Crops, rotation of 110 

Crystallizing 19 

Crystals of snow 17 

Cultivation 100 

deep 107 

of hoed crops 107 

purposes of 100-103 

shallow . 107 



D. 

Dark weather, effect of . . . 61 

Decomposition 20 

of soil 101 

Deep cultivation ...... 107 

Deep plowing 104 

Dew 48 

Diamonds 21 

Diffusion 65 

in plants 68, 72 

Digestible parts of food . . . 121 

Digestion 133 

Disks of the blood 138 

Drainage, by deep tillage . . . 104 

Draining .' 108 

cold soil ,110 

Drains, to prevent effect of 

drought 109 



Earth, its original condition . . 26 

its age . 29 

its interior 26 

Earthquakes 26 

Economy in feeding . . . 122, 123 

Effect of agriculture .... 78 

Effervescence 14 

Elementary substances ... 8 



INDEX. 



149 



Equations, chemical 
Erigenia .... 
Evaporation from soil 
Excretion .... 
Exposure of manure 



Page 

12 

63 

110 

138 

94 



F. 

Farm, care of 92 

Farm manure 90 

nature of 90, 91 

Fat, animal 115 

in food 119 

varieties of ... . 115, 116 

Feed, true cost of 132 

Fermentation of manure ... 92 

Fertile soil 77 

Fertility 37 

maintained 79 

reduced by weeds .... 102 

Fertilizers 77 

artificial 83 

prepared 85 

Fiber in foods 120 

of wood 70 

Fibrous roots 63 

Flow of sap 65,72 

Flowers 73 

Fogs 47 

Food of plants 60, 65 

Food, purposes of . . . 116, 117 
digestible parts of ... . 122 
quantity profitable . . . 124 

variety of 129 

Foods, composition of . . 118, 121 
double value of . . . 131, 132 
manurial value of . . 129, 130 

true cost of 132 

value of 122 

G. 

Germ of seeds 54 

Germination 57 

Glaciers 34 

Glands, salivary 133 

Glass 22 

Granite 22 

soil from 79 

Graphite 23 



Page 

Gravelly soil 38 

Growth, of roots 63 

of plants . . „ . . . 68, 69 

Guano 85 

Gullet, the ........ 135 

Gum arable 12 

Gypsum 13, 87, 88 

H. 

Hail 47 

Hard pan 31 

Harrowing, purposes of . . . 106 

thorough 106 

Health of animals 139 

Heat, effect of 16 

animal 117 

in germination 58 

Herbivorous animals .... 114 

Hills 32 

formation of 29, 30 

worn away b}- winds ... 35 

Hoed crops, cultivation of . . 107 

Humus 35 

Hydrochloric acid . . . 11-13, 22 

Hydrogen 20 

I. 

Ice, effect of, upon soil .... 32 

Impurities of the atmosphere . 42 

Indian corn, roots of ... . 64 

mixture of 74 

Insects, avoided by rotation . . 112 

Intestines, the 133 

length of 133 

Iron 125 

K, 

Kidneys, the 138 

Kindness to animals .... 140 

L. 

Lacteals, the 134 

Leguminous plants 62 

Lime 12, 13, 19, 41, 86 

benefit of, in soil .... 87 
Limestone 23, 32, 37 



150 



INDEX. 



Page 

Limestone, soil from .... 79 

Limy soil 41 

Liquid manure 94 

Litmus 66 

Loam 39 

Lucerne 62 

JiUngs, the 138 

M. 
Magnesia . . . . . . 13, 23 

Manure 90 

application of .... . 94 

fermentation of 92 

from foods, value of . . . 131 

losses of 92, 93, 94 

Manurial value of foods 129, 130, 131 

Marble 23, 31 

Marl 87 

Mastication 133 

Matter, nature of 10 

Mist 47 

Moisture of climate .... 51, 52 
in germination .... 55, 58 
regulated by cultivation . 103 
withdrawn by weeds . . . 102 

Mold, vegetable 79 

Molecules 9 

Mountains . . o . . . . 29, 32 

formation of 27 

Mouth, the 133 

Mouths of leaves 61 

Muck 95, 96 

value of 96, 97 

Muck beds 35 

Mucky soil 39 

Muriate of potash 85 

Muriatic acid 13, 22 

N. 
Nitrate of lime 82 

of potash 82 

of soda 13, 82, 84 

Nitrates 82 

in soil 81 

Nitric acid 13 

in soil 81, 82 

Nitrification 82, 83 

Nitrogen ... 20, 41, 62, 81, 84 



Page 

Nitrogen as food for plants . . 62 
North America, formation of . 27 

Nutrition in plants 72 

Nutriti'^e ratio .... 124, 12G 

O. 

Oak trees, roots of 63 

Ocean, affecting climate ... 51 

soil formed by 32 

Organic matter 17, 18 

Osmose 62 

in plants 71 

Oxidation 19, 20 

of plants 62 

Oxide of iron 13 

Oxides 19 

Oxygen 19, 20 

in germination of plants . 56 

in soil 101 

in the blood 61 

P. 

Paunch, the 134 

Peas 62 

Peat 35, 37 

Peaty soil 35, 39 

Perspiration, effect of . . . . 118 

Petals 74 

Phosphate of lime .... 13, 84 
Phosphoric acid . . 13, 22, 83, 84 

Phosphorus 22 

Pistils 74 

Planting, depth of 57 

Plants, growth of 08 

breathing of 20 

food of ' GO 

instinct of 59 

leguminous G2 

structure of ..... . 68 

Plant food, formation of . . . 101 

Plaster, land 87 

Plowing 103,104 

subsoil 105 

time for 105, 106 

Plumule, the 59 

Pores of wood 15 

Porosity of matter 15 

Potassium 23 



INDEX. 



151 



Page 

Potash 23,83,85 

salts 85 

Potato, cells of 69 

Prepared fertilizers .... 85, 86 

Pressure of the air 43 

Protein ........ 118, 119 

Q. 

Quartz rock 22 

Quicklime 13, 86 

R. 

Radicle, the 59, 62, 63 

Rain 42, 45, 46, 47 

Rainless regions 47 

Rain water, a fertilizer . . . 108 

Ratio, nutritive 125 

Ration, balanced 125 

Rations, how made up .... 127 

examples of 128, 129 

Requirements of animals . . . 127 

Respiration 20 

Rice plants 101 

Rochelle powders 13 

Rocks, ancient 30 

Rolling land 107 

Rootlets 64 

Roots 63, 04 

air necessary for .... 101 

in wet soil 108 

of buttercups 63 

of clover 64 

of the maple 03 

tap 03 

tuberous 03 

Rotation of crops . . . .110-112 

Ruminants 134-136 

stomachs of 134, 135 

Running water, effect of . . . 31 
"Run out "land 79 

S. 

Saliva 133 

Salivary glands 133 

Salt 11, 12, 17, 65, 87 

Saltpeter 84 

Sandstone ^ 22, 31, 32 



Page 

Sandy soil 37, 38, 105 

Sap of plants 65 

flow of -71, 72 

Saturated soil 101 

Sea breezes 45 

Seeds ". . 54 

unripe < 55 

Selection of food by plants . . 73 

Sepals 74 

Shallow cultivation . . . » . 107 

Silicates 22 

Silicon 22, 73 

Silicic acid 13 

Simple substances 7 

Slag 85 

Slaked lime 12 

Smoked glass 21 

Smut 69 

Snow 47 

crvstals 17 

Sodium 13, 23 

Soil, formation of .... 27, 30 

alluvial 105 

composition of . . . 3^, 15, 78 
fertile . ..... 77 

from granite 79 

from limestone 79 

sandy .37, ^8. 105 

warmth of 110 

Solids, liquids, and gases ... 16 
South Carolina rock .... 85 
Squashes, mixture of ... . 74 

Stamens 74 

Starch 60 

of potatoes 69 

Stomach, the .... . 133, 134 
Stomachs of ruminants . . . 135 

Stomata 60, 01 

Storms 50 

Subsoil 104 

plowing 105 

Substances, simple 7 

Success in agriculture .... 141 

Sugar 10, 00 

Sulphates 13,84 

Sulphate of ammo^iia .... 84 

of lime 13 

of potash V 23 

Sulphur 22 

Sulphuric acid . . 10, 13, 21, 22, 66 



152 



INDEX. 



Pagk 

Summer fallowing 101 

bunlight, effect of G2 

T. 

Tap-roots G3 

Temperature 44, 50 

Thermometer 44 

Tillage, deep 104 

Time to plow 1 05 

Timothy grass 73 

Tuberous roots 63 

Turnips 63 

Underdrains 108 

Unripe seeds 55 

Urea 138 

V. 

Valleys, cause of 30 

Value of foods 121, 122 

Variety of food 129 

Vegetable matter 35 

Vegetable mold .... 35, 79 

Vegetable tissue 69 

Vegetation, carboniferous . . 36 
Veins, the 137 



Page 

Vitality of seeds 54 

Volatile substances 21 

W. 

\V"arm wave 49 

Warmth for germination ... 50 

Watei-, magnified 9 

in foods 118 

in the animal bod}' . . . 115 

molecule 11 

vapor 41 

Watering plants 62 

Weather, the 49 

Weeds 102 

Wetland 109 

White clover 63 

Wind 34, 35, 44, 45 

Wood, composition of ... . 7 

Wood, porosit}' of 15 

Work, effect of 117 

Y. 

Young animals 116 

Z. 

Zinc 11, 12 

Zinc chloride 12 



The Natural Geographies 



NATURAL ELEMENTARY GEOGRAPHY 

Linen Binding, Quarto. 144 pages . . . Price 60 cents 

NATURAL ADVANCED GEOGRAPHY 

Linen Binding, Large Quarto, 160 pages . . . Price $1.25 
By Jacques W. Redway, F.R.G.S., and Russell Hinman, 
Author of the Eclectic Physical Geography. 

The publication of The Natural Geographies marks a new era in the 
study and teaching of geography. Some of the distinctive features which 
characterize this new series are : 

1. A Natural Plan of Development, based on physical geography and 

leading in a natural manner to the study of historical, industrial, 
and commercial geography. 

2. Clear and distinct political maps showing correctly the comparative 

size of different countries, and physical maps showing relief by 
contour lines and different colors, as in the best government maps. 

Inductive and comparative treatment of subjects according to the 
most approved pedagogical principles. 

Frequent exercises and reviews leading to the correlation and com- 
parison of the parts of the subject already studied. 

Topical outlines for the language work required by the Courses of 
Study of the best schools. 

Supplementary Exercises including laboratory work and references 
for collateral reading. 

Numerous original and appropriate pictures and graphic diagrams 
to illustrate the text. 

Clear explanations of each necessary term where it first occurs, and 
omission of formal definitions at the beginning of the book. 

Strict accordance, in method and treatment, with the recommenda- 
tions of the Committee of Fifteen. 



Illustrated Circulars describing the plan and method of The Natural 
Geographies will be sent free to any address on application. 

Copies of The Natural Geographies will be sent, prepaid, to any address 
on receipt of the price by the Publishers : 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 



A School History of the United States 

By JOHN BACH McMASTER 

Professor of American History in the University of Pennsylvania 

Linen, 12mo, 507 pages. With nnaps and illustrations . . $1.00 



This new nistory of our country is marked by many 
original and superior features which will commend it alike 
to teachers, students, and general readers. The narrative 
is a word-picture of the great events and scenes of Ameri- 
can history, told in such a way as to awaken enthusiasm 
in the study and make an indelible impression on the 
mind. From the beginning the attention of the student 
is directed to causes and results, and he is thus encouraged 
to follow the best methods of studying history as a con- 
nected growth of ideas and institutions, and not a bare 
compendium of facts and dates. Special prominence is 
given to the social, industrial, and economic development 
of the country, to the domestic life and institutions of the 
people, and to such topics as the growth of inventions, the 
highways of travel and commerce, and the progress of the 
people in art, science, and literature. The numerous 
maps give vivid impressions of the early voyages, explora- 
tions, and settlements, of the chief military campaigns, of 
the territorial growth of the country, and of its population 
at different periods, while the pictures on almost every 
page illustrate different phases in the civil and domestic 
life of the people. 

Copies will be sent, prepaid, on receipt of the price by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(116) 



Milne's Plane and Solid Geometry 

Half Leather, izmo, 384 pages. Price, $1.25 

Milne's Plane Geometry—Separate 

Half Leather, i zmo, 242 pages. Price, ^0.75 

By William J. Milne, Ph.D., LL.D. 
President State Normal College, Albany, N. Y. 



This new text-book in geometry embodies many origi- 
nal methods of treatment, which while novel and attrac- 
tive, are based on sound mathematical and pedagogical 
principles. The author's aim has been to combine the 
valuable features of inventional and concrete geometry 
with the forms of rigid deductive reasoning, which is one 
of the chief objects sought in this branch of study. 

In this work the student is introduced to geometry 
through the employment of inventional steps, supplemented 
by demonstrations of the fundamental propositions of the 
science. Every theorem is introduced by questions de- 
signed to lead the student to discover the geometrical 
concept clearly and fully before attempting a demonstra- 
tion. The laboratory method is introduced at the be- 
ginning and is continued throughout the book. A great 
abundance of undemonstrated theorems and of unsolved 
problems is supplied for supplementary and original work. 
Summaries showing the subjects covered and the truths 
established in the chapters to which they are appended are 
an original feature of the book. These will be found of 
great practical value to the student, both in reviewing his 
work and in preparing him for advanced steps. The dia- 
grams and other figures used in the demonstrations are all 
that could be desired in a text-book on geometry. 



Copies of Milne* s Geometries will be sent^ prepaid, to any address 
on receipt of the price by the Publishers : 

AMERICAN BOOK COMPANY 

NEW YORK ♦ CINCINNATI ♦ CHICAGO 

C«3) 



Text-Books in Geology 



By JAMES D. DANA, LL.D. 
Late Professor of Geology and Mineralogy in Yale University. 

DANA'S GEOLOGICAL STORY BRIEFLY TOLD . . . $1.15 
A new and revised edition of this popular text-book for beginners in 
the study, and for the general reader. The book has been entirely 
rewritten, and improved by the addition of many new illustrations and 
interesting descriptions of the latest phases and discoveries of the science. 
In contents and dress it is an attractive volume, well suited for its use. 

DANA'S REVISED TEXT-BOOK OF GEOLOGY . . . $1.40 
Fifth Edition, Revised and Enlarged. Edited by William North 
Rice, Ph.D., LL.D., Professor of Geology in Wesleyan University. 
This is the standaj-d text-book in geology for high school and elementary 
college work. While the general and distinctive features of the former 
work have been preserved, the book has been thoroughly revised, enlarged, 
and improved. As now published, it combines the results of the life 
experience and observation of its distinguished author with the latest 
discoveries and researches in the science. 

DANA'S MANUAL OF GEOLOGY $5.00 

Fourth Revised Edition. This great work is a complete thesaurus of 
the principles, methods, and details of the science of geology in its 
varied branches, including the formation and metamorphism of rocks, 
physiography, orogeny, and epeirogeny, biologic evolution, and paleon- 
tology. It is not only a text-book for the college student but a hand- 
book for the professional geologist. The book was first issued in 1862, 
a second edition was published in 1874, and a third in 1880. Later 
investigations and developments in the science, especially in the geology 
of North America, led to the last revision of the work, wliich was most 
thorough and complete. This last revision, making the work substantially 
a new book, was performed almost exclusively by Dr. Dana himself, and 
may justly be regarded as the crowning work of his life. 



Copies of any of Dana^s Geologies will be sent, prepaid, to any address on 
receipt of the price. 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 



Primers in 
Science, History, and Literature 



Bound uniformly in flexible cloth, 18mo 



Price, 35 cents each 



SCIENCE PRIMERS 
Edited by Professors HUXLEY, ROSCOE, and STEWART 



introductory T. H. Huxley 

Chennistry H, E. Roscoe 

Physics Balfour Stewart 

Physical Geography A. Geikie 

Geology A. Geikie 

Physiology and Hygiene 

M. Foster and R. S. Tracy 

Astrononny J. N. Lockyer 

Botany J. D. Hooker 



Logic W. S. Jevons 

Inventional Geonnetry 

W, G. Spencer 

Pianoforte Playing F.Taylor 

Political Economy. .W. S. Jevons 
Natural Resources of 

the United States. .J. H. Patton 
Scientific Agriculture. N.T. Lupton 
History of Philosophy. .T. Hunter 



HISTORY PRIMERS 
Edited by J. R. GREEN, M.A. 



Greece C. A. Fyffe 

Rome M. Creighton 

Europe E. A. Freeman 

France Charlotte M. Yonge 

Old Greek Life....]. P. Mahaffy 



Roman Antiquities. .A. S. Wilkins 

Geography George Grove 

Mediaeval Civilization. G. B.Adams 

Roman Constitution A. Tighe 

Egypt F. C. H. Wendel 



LITERATURE PRIMERS 
Edited by J. R. GREEN, M.A. 



American Literature, M. C.Watkins 
English Literature 

Stopford A. Brooke 

English Grammar R. Morris 

English Exercises R. Morris 

English Composition.. John Nichol 



Philology J. Peile 

Shakespeare E. Dowden 

Studies in Bryant J. Alden 

Greek Literature R. C. Jebb 

Homer W. E. Gladstone 

Classical Geography. M. F. Tozer 



Copies sent, prepaid, to any address on receipt of the price. 

American Book Company 



New York 
(103) 



Cincinnati 



Chicago 



Webster's School Dictionaries 

REVISED EDITIONS 



WEBSTER'S SCHOOL DICTIONARIES in their revised form con- 
stitute a progressive series, carefully graded and especially adapted for 
Primary Schools, Common Schools, High Schools, Academies, and pri- 
vate ^udents. These Dictionaries have all been thoroughly revised, 
entirely reset, and made to conform in all essential respects to that great 
standard authority in English, — Webster's International Dictionary. 

WEBSTER'S PRIMARY SCHOOL DICTIONARY . . . $0.48 
Containing over 20,000 words and meanings, vi^ith over 400 
illustrations. 

WEBSTER'S COMMON SCHOOL DICTIONARY . . . $0.72 
Containing over 25,000 words and meanings, with over 500 
illustrations. 

WEBSTER'S HIGH SCHOOL DICTIONARY .... $0.98 

Containing about 37,000 words and definitions, and an appendix 

giving a pronouncing vocabulary of Biblical, Classical, Mythological, 

Historical, and Geographical proper names, with over 800 illustrations. 

WEBSTER'S ACADEMIC DICTIONARY. Cloth, $1.50; Indexed, $1.80 
The Same .... Half Calf, $2.75 ; Indexed, $3.00 
Abridged directly from the International Dictionary, and giving the 
orthography, pronunciations, definitions, and synonyms of the large 
vocabulary of words in common use, with an appendix containing 
various useful tables, with over 800 illustrations. 

SPECIAL EDITIONS 

Webster's Countinghouse Dictionary . . Sheep, Indexed, $2.40 

Webster's Condensed Dictionary . Cloth, $1.44 ; Indexed, 1.75 

The Same . . . Half Calf, $2.75 ; Indexed, 3.00 

Webster's Handy Dictionary 15 

Webster's Pocket Dictionary. Cloth 57 

The Same. Roan Flexible 69 

The Same. Roan Tucks . 78 

The Same. Morocco, Indexed 90 

Webster's American People's Dictionary and Manual . . .48 
Webster's Practical Dictionary 80 



Copies of any of Webster's Dictionaries will be sent, prepaid, to any 
address on receipt of the price by the Publishers : 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

004) 



Zoology and Natural History 



BURNET'S SCHOOL ZOOLOGY 75 cents 

A new text-book for high schools and academies, by a practical 
teacher; sufficiently elementary for beginners and full enough for the 
usual course in Natural History. 

DODGE'S INTRODUCTION TO ELEMENTARY PRACTICAL 

BIOLOGY $1.80 

A laboratory guide for high school and college students, intended to 
develop the power of personal investigation. Under each section ar^ 
given questions on the structure and the physiology of a series of common 
animals and plants typical of their kind. Directions are given for the 
collection and preservation of specimens, for preparing them for exam- 
ination, and for performing simple physiological experiments. 

NEEDHAM'S ELEMENTARY LESSONS IN ZOOLOGY . 90 cents 
A text-book for high schools, academies, normal schools, and prepar- 
atory college classes. Special attention is given to the study by scientific 
methods, laboratory practice, microscopic study, and practical zootomy. 

ORTON'S COMPARATIVE ZOOLOGY $1.80 

Structural and systematic. For use in schools and colleges. The 
distinctive character of this work consists in the treatment of the whole 
Animal Kingdom as a unit; in the comparative study of the development 
and variations of organs and their functions, from the simplest to the 
most complex state; in withholding systematic zoology until the student 
has mastered those structural affinities upon which true classification is 
founded. 

HOLDERS' ELEMENTARY ZOOLOGY $1.20 

A text-book for high school classes and other secondary schools. 

MORSE'S FIRST BOOK IN ZOOLOGY .... 87 cents 
For the study of the lower and plainer forms of animal life. The 
examples presented are such as are common and familiar. 

STEELE'S POPULAR ZOOLOGY $1.20 

For academies, preparatory schools, and general reading. The 
treatment is marked by the same clearness and interest that characterize 
all Professor Steele's text-books in the Natural Sciences. 

TENNEYS' NATURAL HISTORY OF ANIMALS— Revised . . $1.20 

This new edition has been thoroughly revised, the recent changes in 

classification introduced, and the book in all respects brought up to date. 

Copies will be sent, prepaid, to any address on receipt of the price. 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(164) 



Text-Books in Chemistry 



STORER AND LINDSAY'S ELEMENTARY MANUAL OF 

CHEMISTRY $1.20 

A standard manual for secondary schools and colleges. This text- 
book is a thorough revision of Eliot, Storer, and Nichol's Elementary 
Manual of Chemistry, rewritten and enlarged to represent the present 
condition of chemical knowledge, and to meet the demands for a class 
book on Chemistry, at once scientific and clear in method. It presents 
the leading facts and theories of the science in such a simple and concise 
manner that they may be readily understood and applied by the student. 

CLARKE'S ELEMENTS OF CHEMISTRY . . . . $1 20 

A scientific book for high schools and colleges intended to provide 
a complete course for schools and to serve as a substantial basis for 
further study. 

COOLEY'S NEW TEXT-BOOK OF CHEMISTRY . . 90 cents 
An elementary course designed for use in high schools and acad- 
emies. The fundamental facts and principles are treated in a simple, 
concise, and accurate manner. 

STEELE'S POPULAR CHEMISTRY $1.00 

A popular treatise for schools and private students in which the 
study is made interesting as well as instructive by the clearness and sim- 
plicity of the treatment. 

BREWSTER'S FIRST BOOK OF CHEMISTRY . . 66 cents 

Designed to serve as a guide for beginners in the simplest prelimi- 
nary chemical operations. The experiments are of the most elementary 
character, and only the simplest apparatus is employed. 



Laboratory Methods 



ARMSTRONG AND NORTON'S LABORATORY MANUAL OF 

CHEMISTRY 50 cents 

COOLEY'S LABORATORY STUDIES IN CHEMISTRY . 50 cents 

KEISER'S LABORATORY WORK IN CHEMISTRY . . 50 cents 

IRISH'S QUALITATIVE ANALYSIS FOR SECONDARY 

SCHOOLS 50 cents 

STODDARD'S OUTLINES OF QUALITATIVE ANALYSIS . 75 cents 



Copies will be sent, prepaid, to any address on receipt of the price, 

American Book Company 
New York « Cincinnati ♦ Chicago 



(i6o) 



V. 



-^\^^UA 



^^M 









LIBRARY OF CONGRESS 



DDDESfimDH'^ 












w0&0^-i 






;.h!^' 



